Saturday

April 19, 2014

April 19, 2014

**Recent Homework Questions About Statistics**

Post a New Question | Current Questions

**Statistics**

The answer is A, Math guru know what he be doin!
*Monday, March 3, 2014 at 2:36pm*

**statistics**

On the average five customers visit a children department store each hour. Using Poisson distribution, calculate the probability of three customers shop at the store.
*Monday, March 3, 2014 at 12:17pm*

**Statistics/Probability**

sw
*Sunday, March 2, 2014 at 3:47pm*

**statistics**

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability related to the Z score. Percentile rank is the proportion below a particular score. OR… http://davidmlane.com/hyperstat/...
*Sunday, March 2, 2014 at 1:59pm*

**Statistics**

99% = mean ± 2.575 SEm SEm = SD/√n Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability related to the Z score. To include each end, double proportion.
*Sunday, March 2, 2014 at 1:54pm*

**Statistics (?)**

Data missing.
*Sunday, March 2, 2014 at 1:50pm*

**statistics**

the average score on the statistics quiz was a 70, and there was a standard deviation of 10 points. If the z-socre was -1.0 what is the percentile rank?
*Sunday, March 2, 2014 at 1:04pm*

**Statistics**

In a certain city of several million people, of the adults are unemployed. If a random sample of adults in this city is selected, approximate the probability that at least in the sample are unemployed. Use the normal approximation to the binomial with a correction for ...
*Saturday, March 1, 2014 at 8:56pm*

**Statistics**

An economist found that a random sample of 42 high school teachers had an average annual salary of $56,490. A previous study showed that the population standard deviation is $4150. Calculate the margin of error, E, for a 99% confidence interval for µ, the average annual ...
*Saturday, March 1, 2014 at 5:26pm*

**statistics**

Either-or probabilities are found by adding the individual probabilities. .43 + .14 = ?
*Saturday, March 1, 2014 at 12:57pm*

**statistics**

A survey among US adults of their favorite toppings on a cheese pizza reported that 43% favored pepperoni, 14% favored mushrooms, and 6% favored both pepperoni and mushrooms. What is the probability that a random adult favored pepperoni or mushrooms on their cheese pizza? ...
*Friday, February 28, 2014 at 8:56pm*

**Probability**

Statistics show that about 5% of all males are colorblind. Suppose that 20 males are selected at random. What is the probability that at least 4 of the 20 people are colorblind? My answer: I got 1-0.984 The answer key says 0.00257394
*Friday, February 28, 2014 at 7:49pm*

**Statistics**

0.0213
*Friday, February 28, 2014 at 7:47pm*

**statistics**

ewrw 6546
*Friday, February 28, 2014 at 6:00pm*

**statistics**

You are gaining information about the population. You are estimating the difference in population means by using the difference in the sample means. You also make a few assumptions, such as the populations have the same variance and the populations are normally distributed.
*Friday, February 28, 2014 at 5:42pm*

**statistics**

When calculating a confidence interval for the difference between two means, what information are you gaining? The means are from both same population and different? Thank you.
*Friday, February 28, 2014 at 4:47pm*

**Math (Statistics)**

Perfect data, one standard of devation below and above. so appr 68% or prob of .68 confirmed by David's webpage http://davidmlane.com/hyperstat/z_table.html fill in the data to see and get .6827
*Friday, February 28, 2014 at 3:54pm*

**Math (Statistics) **

The SAT scores of a certain population of students are approximately normally distributed with a mean and standard deviation of 1000 and 200 points, respectively. The probability that a student selected at random from the population has an SAT score between 800 and 1200 ...
*Friday, February 28, 2014 at 3:20pm*

**Statistics**

Are the means from the same population or different?
*Friday, February 28, 2014 at 2:32pm*

**Statistics**

If "the probability of birth is equal in all months," that means that you would expect 10 students to be born in each month. Would either distribution apply in this case?
*Friday, February 28, 2014 at 2:30pm*

**Statistics**

Assume it is known that the probability of birth is equal in all months. What is the probability that in the STAT class of 120 students, exactly 20 students have their birthdays in either August or September? Solve using (i) the exact Binomial distribution, (ii) the Normal ...
*Friday, February 28, 2014 at 9:56am*

**Statistics**

Never mind, figured it out :)
*Friday, February 28, 2014 at 9:28am*

**Statistics**

.68
*Friday, February 28, 2014 at 9:10am*

**Statistics**

Two of the biggest soft drink rivals, Pepsi and Coke, are very concerned about their market shares. The pie chart that follows claims that PepsiCo's share of the beverage market is 25%. Assume that this proportion will be close to the probability that a person selected at ...
*Friday, February 28, 2014 at 9:02am*

**Statistics**

When calculating a confidence interval for the difference between two means, what information are one gaining?
*Friday, February 28, 2014 at 8:49am*

**Statistics**

Nevermind! I figured out what I did wrong!
*Friday, February 28, 2014 at 12:24am*

**Statistics **

Let X be a binomial random variable with n = 100 and p = 0.2. Find approximations to these probabilities. (Round your answers to four decimal places.) P(17 < X < 28) I get the answer as 0.7059 but it is wrong. I can't seem to figure this out... Help please
*Thursday, February 27, 2014 at 11:57pm*

**engineering**

Building and construction A. Architecture B. Engineering C. Nursing D. Statistics
*Thursday, February 27, 2014 at 8:53pm*

**Statistics in Psychology**

a) Looks like a paired t-test (same subjects are used in a "before and after" scenario). b) Looks like an independent groups t-test (different subjects) c) Looks like a matched pairs t-test (matched based on characteristics like age).
*Thursday, February 27, 2014 at 5:27pm*

**Statistics**

Looks like an ANOVA design. If there were significant differences, then the test was statistically significant.
*Thursday, February 27, 2014 at 5:02pm*

**Statistics**

See previous post.
*Thursday, February 27, 2014 at 4:59pm*

**statistics**

0
*Thursday, February 27, 2014 at 4:04pm*

**statistics**

Aaa
*Thursday, February 27, 2014 at 3:39pm*

**statistics**

Z = (score-mean)/SD Either use the handout or find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability related to the Z score.
*Thursday, February 27, 2014 at 2:42pm*

**Statistics**

THE ANSWER IS 23! Don't listen to math guru. He lies
*Thursday, February 27, 2014 at 1:53pm*

**statistics**

6.416
*Wednesday, February 26, 2014 at 9:13pm*

**Statistics**

Don't have a TI-84 calculator, but.... Z = (score-mean)/SD Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability (.80) related to a Z score. Insert that value into the above ...
*Wednesday, February 26, 2014 at 12:32pm*

**behavioral statistics**

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportions/probabilities to compare their Z scores (the most common type of standard score).
*Wednesday, February 26, 2014 at 12:23pm*

**statistics**

You have a score on a national entrance exam of 95. What percentage of people in the population have a score that is lower than yours? (Assume the population mean is 75 and the standard deviation is 10. Use the table I passed out in class.)
*Wednesday, February 26, 2014 at 11:47am*

**Statistics**

A report says that the between-subjects factor of participants’ salary produced significant differences in self-esteem. (a) What does this tell you about the design? (b) What does it tell you about the results?
*Wednesday, February 26, 2014 at 10:43am*

**Statistics**

A report says that the between-subjects factor of participants’ salary produced significant differences in self-esteem. (a) What does this tell you about the design? (b) What does it tell you about the results? 19.(a) Source Sum Squares df Mean Square F Between 134.800 3 ...
*Wednesday, February 26, 2014 at 10:41am*

**Statistics in Psychology**

Please Help! For the following, which type of t-test is required? (a) Studying the effects of a memory drug on Alzheimer’s patients, testing a group of patients before and after administration of the drug. (b) Studying whether men and women rate the persuasiveness of an ...
*Wednesday, February 26, 2014 at 9:11am*

**Statistics**

Thank you! :)
*Wednesday, February 26, 2014 at 7:56am*

**behavioral statistics**

How could you use standard scores and the standard distribution to compare the reading scores of two students receiving special reading resource help and one student in a standard classroom who does not get special help?
*Tuesday, February 25, 2014 at 8:29pm*

**statistics**

I'll get you started. CI90 = p ± (1.645)[√(pq/n)] ...where p = x/n, q = 1 - p, and n = sample size. Note: ± 1.645 represents 90% confidence interval. For p in your problem: 26/40 For q in your problem: 14/40 n = 40 I let you take it from here to ...
*Tuesday, February 25, 2014 at 7:30pm*

**statistics**

Use a confidence interval formula for proportions. Here's one example: CI99 = p + or - (2.58)(sqrt of pq/n) ...where sqrt = square root, p = x/n, q = 1 - p, and n = sample size. p = 120/400 q = 280/400 n = 400 Convert all fractions to decimals before using the formula to ...
*Tuesday, February 25, 2014 at 7:17pm*

**Statistics**

The weights of male babies less than 2 months old in the United States is normally distributed with a mean of 11.5 pounds and a standard deviation of 2.7 pounds. Find the 80th percentile score for these weights. I don't have a table, I have to figure it out using the TI-84...
*Tuesday, February 25, 2014 at 7:13pm*

**Statistics**

The law of large numbers tells us what happens in the long run. Like many games of chance, the numbers racket has outcomes so variable - one three-digit number wins $600 and all others win nothing - that gamblers never reach "the long run." Even after many bets, ...
*Tuesday, February 25, 2014 at 7:10pm*

**Statistics**

Substitute 16 for x and solve for tread depth in the equation.
*Tuesday, February 25, 2014 at 7:09pm*

**Statistics 101**

Probably the better answer would be "wider" than 90% confidence interval.
*Tuesday, February 25, 2014 at 7:02pm*

**Statistics**

Try z-scores: z = (x - mean)/sd Substitute the data into the above formula and solve for x. mean = 11.5 sd = 2.7 z = score from the table Use the table to find z-score at the 80th percentile. I'll let you take it from here.
*Tuesday, February 25, 2014 at 6:59pm*

**Statistics**

.0051
*Tuesday, February 25, 2014 at 6:59pm*

**Statistics 101**

...greater than 90% confidence interval.
*Tuesday, February 25, 2014 at 6:56pm*

**statistics**

I'll get you started. Hypotheses: Ho: µ = 12 --> this is the null hypothesis Ha: µ ≠ 12 ---> this is the alternate or alternative hypothesis Note: Null hypothesis always uses an equals sign. The alternate or alternative hypothesis in this case uses ...
*Tuesday, February 25, 2014 at 6:48pm*

**Statistics 101**

A researcher plans to use a random sample of n= 500 families to estimate teh mean monthly family incomefor a large population. a 99% confidence interval based on the sample would be _________ than 90% confidence interval.
*Tuesday, February 25, 2014 at 6:43pm*

**Statistics**

The weights of male babies less than 2 months old in the United States is normally distributed with a mean of 11.5 pounds and a standard deviation of 2.7 pounds. Find the 80th percentile score for these weights.
*Tuesday, February 25, 2014 at 6:18pm*

**Statistics**

The law of large numbers tells us what happens in the long run. Like many games of chance, the numbers racket has outcomes so variable - one three-digit number wins $600 and all others win nothing - that gamblers never reach "the long run." Even after many bets, ...
*Tuesday, February 25, 2014 at 5:39pm*

**Statistics**

(29-25)/4= 4/4= 1
*Tuesday, February 25, 2014 at 5:35pm*

**statistics**

Suppose a manufacturer claims that each family-size bag of pretzels sold weighs 12 ounces on average with a standard deviation of 0.8 ounces. A consumer's group decides to test this claim. If a simple random sample of 49 bags of pretzels gives a sample mean of 11.8 ounces...
*Tuesday, February 25, 2014 at 5:31pm*

**Statistics**

It is 99%, sorry for the typo.
*Tuesday, February 25, 2014 at 4:30pm*

**Statistics**

The law of large numbers tells us what happens in the long run. Like many games of chance, the numbers racket has outcomes so variable - one three-digit number wins $600 and all others win nothing - that gamblers never reach "the long run." Even after many bets, ...
*Tuesday, February 25, 2014 at 3:13pm*

**Statistics**

Suppose x has a distribution with μ = 11 and σ = 5. (a) If a random sample of size n = 45 is drawn, find μx, σ x and P(11 ≤ x ≤ 13). (Round σx to two decimal places and the probability to four decimal places.)
*Tuesday, February 25, 2014 at 1:31pm*

**Statistics**

95% = mean ± 2.575 SEm SEm = SD/√n I'll let you do the calculations.
*Tuesday, February 25, 2014 at 1:30pm*

**Statistics**

A class survey in a large class for first-year college students asked, "About how many minutes do you study on a typical weeknight?" The mean response of the 463 students was x = 118 minutes. Suppose that we know that the study time follows a Normal distribution with...
*Tuesday, February 25, 2014 at 11:11am*

**Statistics **

In a study, nine tires of a particular brand were driven on a track under identical conditions. Each tire was driven a particular controlled distance (measured in thousands of miles), and afterward the tread depth was measured. Tread depth is measured in “mils.” Here...
*Tuesday, February 25, 2014 at 7:23am*

**statistics**

Determining whether an individual's political affliation affects his or her overall satisfaction with the economy. For this assignment, use only subjects that declared themselves as Republicans or Democrats and leave out any subjects who declared themselves as Independent ...
*Tuesday, February 25, 2014 at 12:47am*

**statistics**

A psychic was tested for ESP. The psychic was presented with 400 cards face down and was asked to determine if the card was one of four symbols: a cross, a star, a circle, or a square. The psychic was correct in 120 of the cases. Let p represent the probability that the ...
*Monday, February 24, 2014 at 7:25pm*

**statistics**

An SRS of 40 San Diego County Schools graduates showed that 26 of the 40 enrolled in a college or university right out of high school. a. Find a 90% confidence interval for the proportion of all San Diego County Schools graduates who enrolled in a college or university right ...
*Monday, February 24, 2014 at 6:19pm*

**Statistics**

Either-or probabilities are found by adding the individual probabilities. Since three face cards are already spades, delete them for the face card probability. 9/52 + 13/52 = ?
*Monday, February 24, 2014 at 1:26pm*

**statistics**

Please only post your questions once. Repeating posts will not get a quicker response. In addition, it wastes our time looking over reposts that have already been answered in another post. Thank you. See your later post.
*Monday, February 24, 2014 at 1:14pm*

**statistics**

95% = mean ± 2 SD Find the mean first = sum of scores/number of scores Subtract each of the scores from the mean and square each difference. Find the sum of these squares. Divide that by the number of scores to get variance. Standard deviation = square root of variance ...
*Monday, February 24, 2014 at 1:13pm*

**Statistics (?)**

What blanks? Z = (score-mean)/SD T = 50 + 10Z
*Monday, February 24, 2014 at 1:11pm*

**Statistics**

Fill in the blanks with the appropriate raw score, z score, t scores . Mean =50, sd = 5. Raw 35
*Sunday, February 23, 2014 at 10:16pm*

**statistics **

Construct a 95% confidence interval for the population mean. 5. Airfare A random sample of airfare prices (in dollars) for a one-way ticket airfare between two cities MN. Key: 21|1=211 21 | 1 2 22 | 1 1 1 2 3 5 7 8 23 | 2 3 4 7 7 8 9 9 24 | 2 3 4 8 8 25 | 1 2 6 6 6 6 8 9
*Sunday, February 23, 2014 at 9:37pm*

**statistics**

Construct a 95% confidence interval for the population mean. 5. Airfare A random sample of airfare prices (in dollars) for a one-way ticket airfare between two cities MN. Key: 21|1=211 21 | 1 2 22 | 1 1 1 2 3 5 7 8 23 | 2 3 4 7 7 8 9 9 24 | 2 3 4 8 8 25 | 1 2 6 6 6 6 8 9
*Sunday, February 23, 2014 at 9:29pm*

**math statistics/probability**

rfwd
*Sunday, February 23, 2014 at 9:19pm*

**Statistics**

Summarize the steps involved in analyzing the results of a one-sample experiment.
*Sunday, February 23, 2014 at 2:29am*

**Statistics**

If you pick a card at random from a well shuffled deck what is the probability you will pick a face card or a spade?
*Saturday, February 22, 2014 at 4:08pm*

**statistics**

Z = (mean1 - mean2)/standard error (SE) of difference between means SEdiff = √(SEmean1^2 + SEmean2^2) SEm = SD/√n If only one SD is provided, you can use just that to determine SEdiff. Find table in the back of your statistics text labeled something like "...
*Saturday, February 22, 2014 at 12:47pm*

**Statistics**

Please read and follow directions.
*Saturday, February 22, 2014 at 12:33pm*

**statistics**

a packaging device is set to fill detergent powder packets with a mean weight of 5kg.The standard deviation is known to be .01kg.these are known to drift upwards over a period of time due to machine fault which is not tolerable. A random sample of 100 packets is taken and ...
*Saturday, February 22, 2014 at 9:48am*

**Statistics**

Please read and follow directions.
*Friday, February 21, 2014 at 10:06pm*

**statistics**

Use a table of t-values to estimate the P-value for the specified one-mean t-test. Left-tailed test, n=12, t= -3.412. a=p<0.005. b= p>0.005. c= 0.005<p<0.01.
*Friday, February 21, 2014 at 8:09pm*

**statistics**

µ = 30 Variance for distribution of means = (SD/√n)^2 = ?
*Friday, February 21, 2014 at 4:38pm*

**Statistics**

Most problems of the "at least" type are best done by subtracting from total. P(at least one x) = 1 - P(no x's) = 1 - (25/26)^3 = 0.111 (3dp) So, Yes, you are correct.
*Friday, February 21, 2014 at 12:14pm*

**Statistics**

Selecting a letter of the alphabet: If 3 letters of the alphabet are selected at random, find the probability of getting at least one letter "x". Letters can be used more than once. My answer was: P(at least 1 "x) = 1 - (25/26)^3 = 1951/17576 or 0.11 Is this ...
*Friday, February 21, 2014 at 11:56am*

**statistics**

a. Ok b. 10/23 C. 12/77
*Friday, February 21, 2014 at 12:28am*

**statistics**

Simple question I may be over thinking 30. Gift Baskets: The Gift Basket Sore had the following premade gift baskets containing the following combinations in stock. cookies mugs candy -------------------------------------- coffee 20 13 10 tea 12 10 12 Choose 1 basket at random...
*Thursday, February 20, 2014 at 11:55pm*

**statistics**

A population is normally distributed with mean 30, population SD =10, Sample size 25. What are the mean and variance of the distribution of means, respectively?
*Thursday, February 20, 2014 at 10:35pm*

**Statistics**

Astronomers treat the number of stars in a given volume of space as a Poisson random variable. The density in the Milky Way Galaxy in the vicinity of our solar system is one star per 16 cubic light years. (a) What is the probability of three or more stars in 16 cubic light ...
*Thursday, February 20, 2014 at 8:16pm*

**Statistics**

An electronic product contains 32 integrated circuits. The probability that any integrated circuit is defective is 0.02, and the integrated circuits are independent. The product operates only if there are no defective integrated circuits. What is the probability that the ...
*Thursday, February 20, 2014 at 7:41pm*

**Statistics**

See previous post.
*Thursday, February 20, 2014 at 1:34pm*

**Statistics**

If you are comparing two means, you need to have the SEm, which requires knowledge of n. You do not supply that value. Z = (mean1 - mean2)/standard error (SE) of difference between means SEdiff = √(SEmean1^2 + SEmean2^2) SEm = SD/√n If only one SD is provided, you ...
*Thursday, February 20, 2014 at 1:33pm*

**Statistics**

man this !@#$%^& too hard im out !@#$%^&h
*Thursday, February 20, 2014 at 2:18am*

**Statistics**

suck my anus
*Thursday, February 20, 2014 at 2:15am*

**Statistics**

m m
*Thursday, February 20, 2014 at 2:00am*

**Statistics**

P(A and B) = P(A) * P(B/A) = (0.81)* (0.92) = 0.745 The probability that a U.S. household selected at random has a computer and has Internet access is 0.745
*Thursday, February 20, 2014 at 1:10am*

**Statistics**

2. On a certain anxiety questionnaire, the population is known to have a mean of 12 and a standard deviation of 2.3. A higher score represents higher levels of anxiety. Participants in a new relaxation program complete the questionnaire after completing the program, and have a...
*Wednesday, February 19, 2014 at 11:22am*

**Statistics**

1. A company decides to add a new program that prepares randomly selected sales personnel to increase their number of sales per month. The mean number of sales per month for the overall population of sales people at this national company is 25 with a standard deviation of 4. ...
*Wednesday, February 19, 2014 at 11:20am*

**Statistics (?)**

More data is needed for us to provide help.
*Wednesday, February 19, 2014 at 11:03am*

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