# the mean number of hours per week spent playing video games was 21.6. The sd=5.7. Calculate the 99% confidence interval for the mean. The format for a confidence interval is

98,112 results

### stats

A research firm conducted a survey to determine the mean amount people spend at a popular coffee shop during a week. They found the amounts spent per week followed a normal distribution, with a population standard deviation of $4. A sample of 49 customers revealed that the ...

### statistics

A film alliance used a random sample of 50 U.S. citizens to estimate that the typical American spent 78 hours watching videos and DVDs last year. The standard deviation of this sample was 9 hours. (a) Develop a 95 percent confidence interval for the population mean number of ...

### Statistics

A confidence interval for a population mean has a margin of error of 3.1. a)Determine the length of the confidence interval. b)If the sample mean is 56.7, obtain the confidence interval.

### AP Statistics

A school psychologist reports that the mean number of hours the students at this school sleep each night is 8 hours. The students believe the mean is not 8 hours. To find an estimate of the true mean, they select a random sample of 15 students from their school and ask how ...

### Stastics

Which of the following descriptions of confidence intervals is correct? (Select all that apply) a. If a 95% confidence interval contains 0, then the 99% confidence interval contains 0 b. If a 99% confidence interval contains 0, then the 95% confidence interval contains 0 c. If...

### RES 341

A sample of 300 is taken and the sample mean is computed to be 7.65 and the sample standard deviation is 5. Assume the data is ratio level. Compute the 95% confidence interval on the mean. Compute the 3.9% confidence interval on the mean Which confidence interval is more ...

### statistics

The average teenager spends 7.5 hours per week playing computer and video games. In a random sample of 110 teenagers, what is the probability that their mean time for playing games is more than 8 hours per week?

### Statistics

A random sample of 90 observations produced a mean that = 25.9 and a standard deviation s =2.4 (a)Find a 95% confidence interval for u (b)Find a 90% confidence interval for u (c)Find a 99% confidence interval for u (Use integers or decimals for any number in the expression. ...

### Statistics

The standard deviation for a population is σ = 15.3. A sample of 36 observations selected from this population gave a mean equal to 74.8. a) Make a 90% confidence interval for μ b) Construct a 95% confidence interval for μ. c) Determine a 99% confidence interval...

### Statistics

Suppose x has a mound-shaped distribution with sigma = 9 . A random sample of size 36 has sample mean 20. Is it appropriate to use a normal distribution to compute a confidence interval for the population mean m? Explain. Find a 95% confidence interval for m. Explain the ...

### Statistics

Can anyone help me with this? Which of the following statements is true about a 99% confidence interval? a. The interval contains 99% of the population. b. The probability that the population mean is in the interval is 99%. c. The interval is wider than a 95% confidence ...

### Statistics

1. A certain population follows a normal distribution, with mean m and standard deviation s = 2.5. You collect data and test the hypotheses H0: m = 1, Ha: m 1. You obtain a P-value of 0.022. Which of the following is true? Why? a. A 95% confidence interval for m will include ...

### INTERVAL OF THE MEAN

In a test of of garlic for lowering cholesterol, 45 subjects were treated with garlic in a processed tablet form. Cholesterol levels were measured beforeandafter the treatment. The changes in their levels of LDL cholesterol (in mg/dL) have a mean of 5.4 and a sd of 17.5. ...

### Statistics

If someone gives you a sample mean and a standard deviation, you can find a confidence interval. But what if someone gives you the confidence interval instead and asks you to find the sample mean? How can you do that? Here's an example: a 95% confidence interval for a mean is ...

### statistics

What do confidence intervals represent? What is the most controllable method of increasing the precision of or narrowing the confidence interval? What percentage of times will the mean, or population proportion, not be found within the confidence interval?

### stats

1. A confidence interval can be calculated to estimate the population mean when the population is normally distributed or the sample size is greater than 30. Can a confidence interval be calculated for the average number of hours of sleep for the US babies using this ...

### Statistics

Which of the following statements correctly interprets a 95% confidence interval on a population mean? a. It is a single point estimate b. Used to quantify the certainty of the sample standard deviation c. A 99% confidence interval is narrower than the 95% confidence interval ...

### Math Statistics

5. Students in an introductory statistics class were asked to report the age of their mothers when they were born. Summary statistics include Sample size: 36 students Sample mean: 29.643 years Sample standard deviation: 4.564 years a. Calculate the standard error of this ...

### statistics

A sample of 352 subscribers to Wired magazine shows the mean time spent using the Internet is 13.4 hours per week, with a sample standard deviation of 6.8 hours. Find the 95 percent confidence interval for the mean time Wired subscribers spend on the Internet.

### Statistics

A 95% confidence interval for a population mean, ?, is given as (18.985, 21.015). This confidence interval is based on a simple random sample of 36 observations. Calculate the sample mean, x ?, and the sample standard deviation, s. Assume that all assumptions and conditions ...

### Statistics

In the third week of July, a random sample of 61 farming regions gave a sample mean of = $6.88 per 100 pounds of watermelon. Assume that is known to be $1.72 per 100 pounds. A farm brings 30 tons of watermelon to market. Find a 98% confidence interval for the population mean ...

### probs & stats

1. A study of 40 people found that they could do on the average15 pull ups with a standard deviation of .6. Find the 99% confidence interval for the mean of the population. 2. A study of 50 pizza delivery workers found that they could make 6 deliveries per hour with a standard...

### Statistics

. As the sample size increases The confidence interval also increases (gets larger) The confidence interval decreases (gets smaller) The confidence interval stays the same The population mean increases.

### Statistics

1. A study of 40 people found that they could do on the average15 pull ups with a standard deviation of .6. Find the 99% confidence interval for the mean of the population. 2. A study of 50 pizza delivery workers found that they could make 6 deliveries per hour with a standard...

### Statistics

Twelve different video games showing substance use were observed and the duration times of game play (in seconds) are listed below. The design of the study justifies the assumption that the sample can be treated as a simple random sample. Use the data to construct a 90% ...

### Statistics

What is meant by the 95% confidence interval of the mean ? That 95% of my sample is OK to do more tests. That I am 95% confident that the confidence interval will contain the parameter being estimated. That 5% of my sample is not OK. That I am 95% sure that the population mean...

### statistics

What is meant by the 95% confidence interval of the mean ? That 95% of my sample is OK to do more tests. That I am 95% confident that the confidence interval will contain the parameter being estimated. That 5% of my sample is not OK. That I am 95% sure that the population mean...

### Confidence Intervals

Over the last 15 Major League Baseball seasons, the mean number of strikeouts by the American League leader is 258.5. Assuming that the number of strikeouts by the league leader is normally distributed and the standard deviation for all seasons in all leagues is 34.9, find the...

### Statistics

Suppose you are told that a 95% confidence interval for the average price of a gallon of regular gasoline in your state is from $2.85 to $3.84. Use the fact that the confidence interval for the mean is in the form x − E to x + E to compute the sample mean and the maximal ...

### statistics

A 90% confidence interval for a population mean based on 144 observations is computed to be (2.7,3.4). How many observations must be made so that 90% confidence interval will specify the mean to within ± 0.2

### statistics

In a sample of 100 steel wires the average breaking strength is 50 kN, with a standard deviation of 2 kN. a. Find a 95% confidence interval for the mean breaking strength of this type of wire. b. An engineer claims that the mean breaking strength is between 49.7 kN and 50.3 kN...

### statistics

A simple random sample of students is selected, and the students are asked how much time they spent preparing for a test. The times (in hours) are as follows: 1.3 7.2 4.2 12.5 6.6 2.5 5.5 Based on these results, a confidence interval for the population mean is found to be...

### Statistics

Biologists studying the healing of skin wounds measured the rate at which new cells closed a razor cut made in the skin of an anesthetized newt. Here are data from 18 newts, measured in micrometers per hour: 29,27,34,40,22,28,14,35,26,35,12,30,23,18,11,22,23,33. Questions: a)...

### Statistics 2

The body temperature of healthy human beings can be assumed to have a normal distribution with mean and standard deviation . Body temperature measurements taken from a sample of 130 healthy individuals shows the sample mean temperature to be 98.249O F and ...

### statistics

A random sample of 16 mid-sized cars tested for fuel consumption gave a mean of 26.4 kilometers per liter with a standard deviation of 2.3. (a) Assuming that the kilometers per liter given by all mid-sized cars have a normal distribution, find a 99% confidence interval for the...

### math

A random sample of 16 mid-sized cars tested for fuel consumption gave a mean of 26.4 kilometers per liter with a standard deviation of 2.3. (a) Assuming that the kilometers per liter given by all mid-sized cars have a normal distribution, find a 99% confidence interval for the...

### statistics

Can someone guide me on how to solve this problem: A sample of 52 night students ages is obtained in order to estimate the mean age of night school students. sample mean = 25.9 years. the population variance is 23. Give a point estimate for the mean. Find the 95% confidence ...

### UOP

5) In a 95% Confidence Interval, the true mean has what chance of falling between the Lower Limit and Upper Limits of the calculated confidence interval? A. .90 B. 95% C. .05 D. 5%

### statistics

The population standard deviation (σ) for a standardized achievement test that is normally distributed is 8. a.) Calculate the standard error of the mean if you draw a random sample of 50 test scores. Show your work for full credit . . . b.) Your sample mean...

### statistics

Pleas HeLp!!!!!!!!!! A random sample of the test scores of 100 applicants for college entry at a large junior college showed a mean score of 72.6. Determine a 99%, 95%, and 90% confidence interval for the m mean score of all applicants at the junior college. Assume the ...

### statistics

A random sample of 16 mid-sized cars tested for fuel consumption gave a mean of 26.4 kilometers per liter with a standard deviation of 2.3 kilometers per liter. i) Assuming that the kilometers per liter given by all mid-sized cars have a normal distribution, find a 99% ...

### Statistics

A researcher performs a hypothesis test to test the claim that among girls aged 9-10, the mean score on a particular aptitude test differs from 72, which is the mean score for boys of the same age. Data were collected from a random sample of 43 girls aged 9-10 years and the 95...

### Statistics

Which of the following statements best describes the uncertainty associated with a 95% confidence interval for a population proportion, computed from a simple random sample? A. We don't know whether the particular confidence interval is successful or not, but 95% of ...

### statistics

Refer to Table 1 in the article “Snail Shells in a Practical Application of Statistical Procedures” in the Electronic Reserve Readings. Find the margin of error, E, with a confidence interval of your choosing (50-99%). What is the significance of choosing a confidence ...

### Basic Statistics

A random sample of 16 mid-sized cars tested for fuel consumption gave a mean of 26.4 kilometers per litre with a standard deviation of 2.3 kilometers per litre. (a)Assuming that the kilometers per litre given by all mid-sized cars have a normal distribution,find a 99% ...

### statistics

Consider a 95% confidence interval for a population mean constructed from a random sample of 250 observations taken from a Normal population. Sigma is known to be 14. If we were to construct another 95% confidence interval, this time using 1,000 observations, how would the ...

### statistics

Consider a 95% confidence interval for a population mean constructed from a random sample of 250 observations taken from a Normal population. Sigma is known to be 14. If we were to construct another 95% confidence interval, this time using 1,000 observations, how would the ...

### Statistics

These are the only ones that I am having problems with. Please help.. 8.You are given the sample mean and the sample standard deviation. Use this information to construct the 90% and the 95% confidence intervals for the population mean. Interpret the results and compare the ...

### Environmental Management

A. The 95% confidence interval is: (a) Larger than the 99% confidence interval (b) Smaller than the 99% confidence interval (c) The same as the 99% confidence interval

### statistics

To determine how many hours per week freshmen college students watch television, a random sample of 225 students was selected. It was determined that the students in the sample spent an average of 35 hours watching TV per week. The population standard deviation is known to be ...

### statistics

A simple random sample of 60 items resulted in a sample mean of 80. The population standard deviation is 15. a) Compute the 95 % confidence interval for the population mean. b) Assume that the same sample mean was obtained from a sample of 120 items. Provide a 95% confidence ...

### Statistics

This is my first stats class and I don't know how to do this, could you please help me? Thank you. You are asked to determine the typical number of sales of a certain product at the store you work for. A sample of 50 days over the last quarter shows an average of 55 units sold...

### statistics HELP!

A data set includes body temperatures of healthy adult humans for which 98.1F and s= 0.56F. What is the best point estimate of the mean body temperature of all healthy humans? Using the sample statistics, construct a confidence interval estimate of the mean body temperature of...

### statistics

A data set includes body temperatures of healthy adult humans for which x= 98.2 and s=0.64 F. Complete parts a) and b) below a) what is the best point estimate of the mean body temperature of all healthy humans? The best point estimate is F. b) Using the sample statistics, ...

### statistics

The Frayed Nerves Anxiety Scale (FNAS) is used to measure the anxiety level of people on a scale from 0 to 1000. Four students were randomly chosen and given the FNAS before their second exam. Their scores were 700, 653, 740, and 707. The standard deviation sigma of the test ...

### Statistics 3

A student union wants to obtain a 90% confidence interval for the proportion of “full time” students who hold a part-time job for 20 hours or more per week. For this purpose, they want to interview a sample of full-time students. They want a margin of error to be at most 0...

### statistics 3.

A student union wants to obtain a 90% confidence interval for the proportion of “full time” students who hold a part-time job for 20 hours or more per week. For this purpose, they want to interview a sample of full-time students. They want a margin of error to be at most 0...

### statistics 3.

A student union wants to obtain a 90% confidence interval for the proportion of “full time” students who hold a part-time job for 20 hours or more per week. For this purpose, they want to interview a sample of full-time students. They want a margin of error to be at most 0...

### Statistics

Please help!! I have no idea how to do this question. 14. A sample of 40 CD’s from your collection showed a mean length of 52.74 minutes with a standard deviation of 13.21 minutes a. Construct the 95 percent confidence interval for the mean. b. Construct the 95 percent ...

### statistics

11. A local health care company wants to estimate the mean weekly elder day care cost. A sample of 10 facilities shows a mean of $250 per week with a standard deviation of $25. What is the 90 percent confidence interval for the population mean?

### Math-Stat Help

In a random sample of 78 teenagers, 32 admit to texting while driving. Construct a 98% confidence interval for the percentage of teenager that text while driving. Start by showing that conditions for constructing a confidence interval are met. 1) Check conditions 2) confidence...

### Statistics

In 1998 a San Diego Reproductive clinic reported 49 live births to 207 women under the age of 40 who had previously been unable to get pregnant. Using the 90% confidence interval calculated above, would it be misleading for the clinic to report a success rate of 25%? A) Yes, ...

### statistics

Randomly selected students participated in an experiment to test their ability to determine when one minute(or sixty seconds) has passed. Forty students yielded a sample mean of 61.8 seconds. Assuming that o= 11.7 seconds, Construct and interpret a 99% confidence interval ...

### Statistics

A simple random sample of 50 female 14-year-olds is selected. The sample mean height of the girls is found to be 62 inches. Assume the height of 14-year-old girls is normally distributed with a standard deviation of 5 inches. 1. Based on these data, a 95% confidence interval ...

### Descriptive Statistics

. Over the last 15 Major League Baseball seasons, the mean number of strikeouts by the American League leader is 258.5. Assuming that the number of strikeouts by the league leader is normally distributed and the standard deviation for all seasons in all leagues is 34.9, find ...

### statistics

Help!!!!!! A confidence interval estimate for the population mean is given to be (39,90, 48.11) If the standard deviation is 11.473 and the sample size is 52 determine the maximum error of the estimate. determine the confidence level used for the given confidence interval

### BIOLOGY - LAB

What is Confidence Interval? Is it better to have a large Confidence Interval or a small Confidence Interval? Briefly explain.

### Statistics

1. A study of 40 people found that they could do on the average15 pull ups with a standard deviation of .6. Find the 99% confidence interval for the mean of the population. 2. A study of 50 pizza delivery workers found that they could make 6 deliveries per hour with a standard...

### Statistics (42)

A simple random sample of 60 items resulted in a sample mean of 96. The population standard deviation is 16. a. Compute the 95% confidence interval for the population mean (to 1 decimal). ( , ) b. Assume that the same sample mean was obtained from a sample of 120 items. ...

### statistics

In a random sample of 50 babies 4 to 7 month old the average number of hours they slept per day turned out to be 14.2 hours with a standard deviation of 1.6 hours find and interpret a 90% confidence interval for the mean number of hours slept by babies at this age

### statistics

In a random sample of 50 babies 4 to 7 month old the average number of hours they slept per day turned out to be 14.2 hours with a standard deviation of 1.6 hours find and interpret a 90% confidence interval for the mean number of hours slept by babies at this age

### MATH (STATS)

To determine the views of a students on a particular campus about fraternities, an 11-point attitude scale was administered to a random sample of 40 students. This survey yielded a sample mean of 6 (the higher the score, the more favorable the view of the fraternities) and a ...

### Statistics

The 95% confidence interval is: (a) Larger than the 99% confidence interval (b) Smaller than the 99% confidence interval (c) The same as the 99% confidence interval

### statistics

A sample of n = 9 has a mean of M = 72 with SS = 162. Use the sample to make a point estimate of ì and to construct the 90% confidence interval for ì. (Round all answers to two decimal places ì = ? ± ? ( ? ) The 90% confidence interval for ì: ( ? , ? )

### statistics

A sample of n = 9 has a mean of M = 72 with SS = 162. Use the sample to make a point estimate of ì and to construct the 90% confidence interval for U. (Round all answers to two decimal places.) U = ? ± ? ( ?) The 90% confidence interval for U: ( ? , ? )

### stat

7. A researcher selects a random sample. A 90% confidence interval for a population mean A) is an interval with margin of error ± 90%. B) has the property that if we repeatedly selected our random sample in exactly the same way, each time constructing a different 90...

### Statistics

Multiple Choice Which of the following statements is true about the 95% confidence interval of the average of a sample? A) 95 of 100 avgs of samples will be within the limits of the confidence interval. B) There is a 95% chance the avg of the population to be within the limits...

### statistics

How large a sample would be needed to form a 90% confidence interval for the mean nicotine content of a brand of cigarettes if the nicotine content has a normal distribution with sigma equal to 8.5 mg and the width of the interval (the length of the confidence interval) equal ...

### Statistics

We have calculated a 95% confidence interval for a proportion and would prefer the confidence interval to be more precise, that is narrower. Using the same sample, we can narrow the confidence interval using which of the following? A) increasing the confidence level B) ...

### Statistics

A study was conducted to estimate the mean amount spent on Christmas gifts for a typical family having two children. A sample of size 150 was taken, and the mean amount spent was $225. Assuming a standard deviation equal to $50, find a 95% confidence interval for , the mean ...

### Statistics

A random sample of 47 students studied for an average of 7.1 hours last week. If the population standard deviation is 1.2 hours, what is the 90% confidence interval for the population mean?

### Math

Suppose a population is sampled and the sample mean is 16.8. The sample standard deviation is 6.0 I am to assume the sample is larger than 30) and the sample size is 65. How do I calculate 95% and 98% confidence intervals. State which interval wider and why please. How would I...

### statistics

A basketball scout randomly selected 144 players and timed how long each player took to perform a certain drill. The times in this sample were distributed with a mean of 8 minutes. The population standard deviation was known to be 3 minutes. A. find the critical value for a 95...

### Math

Calcium is essential to tree growth because it promotes the formation of wood and maintains cell walls. In 1990, the concentration of calcium in precipitation in a certain area was 0.11 milligrams per liter (mg/L). A random sample of 10 precipitation dates in 2007 results in ...

### statistics

A sample of 134 golfers showed that their average score on a particular golf course was 87.43 with a standard deviation of 4.53. Answer each of the following (show all work and state the final answer to at least two decimal places.): (A) Find the 99% confidence interval of the...

### statistics

A sample of 106 golfers showed that their average score on a particular golf course was 87.98 with a standard deviation of 5.39. Answer each of the following (show all work and state the final answer to at least two decimal places.): (A) Find the 90% confidence interval of the...

### Statistics 101

A researcher plans to use a random sample of n= 500 families to estimate the mean monthly family incomefor a large population. a 99% confidence interval based on the sample would be _________ than 90% confidence interval.

### statistics

twelve different vTideo games showing substance use were observed and the duration times of game play (in seconds) are listed below. The design of the study justifies the assumption that the sample can be treated as a simple random sample. Use the sample data to construct a 95...

### Statistics

In a study to estimate a population mean, i start with a sample size 10 and calculate the 95% confidence interval. Suppose i am not satisfied with the size of the confidence interval and want to reduce it by half. Give an estimate of sample size that i need.

### statistics

A student union wants to obtain a 90% confidence interval for the proportion of “full time” students who hold a part-time job for 20 hours or more per week. For this purpose, they want to interview a sample of full-time students. They want a margin of error to be at most 0...

### STATISTICS

Bacterial samples were taken from several surfaces in a daycare and incubated in petri dishes. After that the number of bateria colonies were counted, with the following results 412, 437, 425, 476, 451, 483. 1) construct a 95% confidence interval for the mean number of ...

### mba business reserach methods

Sampling A manufacturing company's quality control personnel have recorded the proportion of defective items for each of 500 monthly shipments of one of the computer components that the company produces. See data below. The company doesn't have time to review all of these. (a...

### MATH Statistics

A student union wants to obtain a 90% confidence interval for the proportion of “full time” students who hold a part-time job for 20 hours or more per week. For this purpose, they want to interview a sample of full-time students. They want a margin of error to be at most 0...

### MATH

The following data represent the asking price of a simple random sample of homes for sale. Construct a 99% confidence interval with and without the outlier included. Comment on the effect the outlier has on the confidence interval. Here is the information: $231,500 $279,900 $...

### Math Stats

The following data represent the asking price of a simple random sample of homes for sale. Construct a 99% confidence interval with and without the outlier included. Comment on the effect the outlier has on the confidence interval. Here is the information: $231,500 $279,900 $...

### statistics

Ok, so I'm trying to do this for my exam review. I get some of it, but not all: An electric utility is examining the relationship between temperature and electricity use in its service region on warm days. The utility has bivariate data detailing the maximum temperature (...

### statistics

Before 33 33 38 33 35 35 40 40 40 31 After 34 28 25 28 35 33 31 28 35 33 Ten different families are tested for the number of gallons of water per day they use before and after viewing a conservation video. Construct a 90% confidence interval for the mean of the differences.

### Statistics

50 apples from an orchard are randomly selected. A mean apple diameter of 2.22 inches is calculated with a margin of error for a 95% confidence interval of ±0.13. What is the interval estimate of the population mean? 1.99 < μ < 2.23 2.09 < μ < 2.35 2.09 <...

### math 3

The following data represent the asking price of a simple random sample of homes for sale. Construct a 99% confidence interval with and without the outlier included. Comment on the effect the outlier has on the confidence interval. Here is the information: $231,500 $279,900 $...