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April 18, 2014

April 18, 2014

**Recent Homework Questions About Statistics**

Post a New Question | Current Questions

**Statistics**

3. The formula for finding sample standard deviation is ________________. a.𝑠=∑1▒𝑥W22;𝑥 ̅^2 b.𝜎^2=(∑1▒(𝑋−𝜇)^2 )/𝑁 c.𝑠^2=(∑1▒(𝑋&#...
*Friday, December 20, 2013 at 7:14pm*

**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 ...
*Friday, December 20, 2013 at 12:33pm*

**Statistics**

http://www.investopedia.com/terms/t/type-ii-error.asp
*Friday, December 20, 2013 at 11:51am*

**Statistics**

http://www.investopedia.com/terms/t/type-ii-error.asp
*Friday, December 20, 2013 at 11:50am*

**Statistics**

By definition, a Type I error is ____. a. rejecting a false H1 b. rejecting a false H0 c. rejecting a true H0 d. rejecting a true H1
*Friday, December 20, 2013 at 8:35am*

**Statistics**

Which of the following is an accurate definition of a Type II error? a. rejecting a false null hypothesis b. rejecting a true null hypothesis c. failing to reject a false null hypothesis d. failing to reject a true null hypothesis
*Friday, December 20, 2013 at 8:33am*

**Statistics**

What is the consequence of a Type II error? a. concluding that a treatment has an effect when it really does b. concluding that a treatment has no effect when it really has no effect c. concluding that a treatment has no effect when it really does d. concluding that a ...
*Friday, December 20, 2013 at 8:32am*

**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 ...
*Friday, December 20, 2013 at 1:07am*

**statistics**

Margin of error : 0.372 95 % confidence interval. (15.228, 15.972)
*Thursday, December 19, 2013 at 9:01pm*

**statistics**

For these 90 times the mean was 15.60 minutes and the standard deviation s=1.80 minutes. Find the margin of error (round to 2 decimal places) and the 95% confidence interval for Julia’s average running time.
*Thursday, December 19, 2013 at 8:54pm*

**Statistics**

Choose d. None of the other choices are correct. Choice a: should read change alpha from .01 to .05. Choice b: should read change from a two-tailed test to a one-tailed test. Choice c: should read change sample size n = 25 to n = 100.
*Thursday, December 19, 2013 at 5:33pm*

**Statistics**

Thank you for you held once again your awesome.
*Thursday, December 19, 2013 at 4:57pm*

**Statistics**

When is there a risk of a Type II error? a. whenever H0 is rejected b. whenever H1 is rejected c. whenever the decision is "fail to reject H0" d. The risk of a Type II error is independent of the decision from a hypothesis test.
*Thursday, December 19, 2013 at 4:01pm*

**Statistics**

Which of the following will increase the power of a statistical test? a. Change ƒÑ from .05 to .01. b. Change from a one-tailed test to a two-tailed test. c. Change the sample size from n = 100 to n = 25. d. None of the other options will increase power.
*Thursday, December 19, 2013 at 4:01pm*

**statistics**

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability (.25) and its Z score. Insert Z and other data into equation below and calculate. Z = (score-mean)/SD
*Thursday, December 19, 2013 at 1:27pm*

**probability & statistics**

m = (12-5)/(11-(-9) m =7/20 y = mx + b 5 = -9(7/20) +b 5 = -63/20 + b 163/20 = b y-intercept (0,163/20)
*Wednesday, December 18, 2013 at 5:57pm*

**statistics **

Solve the problem. Round to the nearest tenth unless indicated otherwise. The amount of rainfall in January in a certain city is normally distributed with a mean of 4.3 inches and a standard deviation of 0.3 inches. Find the value of the quartile .
*Wednesday, December 18, 2013 at 5:44pm*

**probability & statistics**

Find the slope and the y-intercept for the line that passes through (-9,5) (11,12)
*Wednesday, December 18, 2013 at 4:33pm*

**Statistics**

A national opinion poll found that 44% of all American adults agree that parents should be given vouchers good for education at any public or private school of their choice. Suppose that in fact the population proportion who feel this way is p=0.44. A) Many opinion polls have ...
*Tuesday, December 17, 2013 at 7:24pm*

**Statistics**

How would you check the Z table for the first problem?
*Tuesday, December 17, 2013 at 7:09pm*

**Statistics 3**

See your latest post.
*Tuesday, December 17, 2013 at 7:08pm*

**Statistics 4**

See your later post.
*Tuesday, December 17, 2013 at 7:07pm*

**statistics 4.**

See your later post.
*Tuesday, December 17, 2013 at 7:00pm*

**statistics 3.**

See your later post.
*Tuesday, December 17, 2013 at 7:00pm*

**statistics 4.**

Here are a few ideas to get you started. First problem: Try a one-sample z-test. Formula: z = (sample mean - population mean)/(standard deviation divided by the square root of sample size) Your data: sample mean = 2.6 population mean = 2.5 standard deviation = 0.5 sample size...
*Tuesday, December 17, 2013 at 6:42pm*

**statistics 3.**

Here are a few ideas to get you started. First problem: Use a formula to find sample size. Here is one for proportions: n = [(z-value)^2 * p * q]/E^2 ... where n = sample size, z-value is 1.645 (90% confidence interval), p = .5 (when no value is stated), q = 1 - p, ^2 means ...
*Tuesday, December 17, 2013 at 6:26pm*

**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 ...
*Tuesday, December 17, 2013 at 5:23pm*

**statistics 4.**

The manufacturer of Porshe 918 Spyder car claims that their car can go from 0 mph to 60 mph speed in less than 2.5 seconds. To test this claim, a sample of 40 new cars of this type were driven and their average 0-60 mph time was 2.6 seconds with a standard deviation of 0.5 ...
*Tuesday, December 17, 2013 at 5:23pm*

**statistics-PLEASE HELP quick**

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.
*Tuesday, December 17, 2013 at 2:48pm*

**statistics**

This is probably too late, but does "etc." include the mean and standard deviation?
*Tuesday, December 17, 2013 at 2:47pm*

**statistics**

a) Ho: mean heights = Ha: mean heights ≠ b) SEm = SD/√n c) Z = (score-mean)/SEm 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. d) Once you ...
*Tuesday, December 17, 2013 at 2:39pm*

**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 ...
*Tuesday, December 17, 2013 at 2:20pm*

**statistics 4.**

The manufacturer of Porshe 918 Spyder car claims that their car can go from 0 mph to 60 mph speed in less than 2.5 seconds. To test this claim, a sample of 40 new cars of this type were driven and their average 0-60 mph time was 2.6 seconds with a standard deviation of 0.5 ...
*Tuesday, December 17, 2013 at 2:19pm*

**statistics**

proportion = 112/250 = .448 z = (.448 - .47) / sqrt(.47*.53/250) = -0.70 p-value = .2420 Since the p-value is greater than .05, do not reject the null hypothesis. The claim is not supported.
*Monday, December 16, 2013 at 11:17pm*

**statistics**

Use a 1.15 level of significance to test a claim that a true proportion is less than 47% when n=250 and x-112
*Monday, December 16, 2013 at 11:07pm*

**statistics-PLEASE HELP quick**

A family has four children and we assume that births occur with equal frequency for both sexes. Construct a sample space for all possible family arrangements allowing for order of birth to count. a) How many different arrangements are possible? b)find P (three are boys)= c)...
*Monday, December 16, 2013 at 11:05pm*

**statistics**

Z = (score -mean) /sd z = (126.2-135)/4 z = -9.8/4 = -2.45 z-table
*Monday, December 16, 2013 at 11:04pm*

**statistics**

4. Are women getting taller? In one state, the average height of a woman aged 20 years or older is 63.7 inches in 1990. A random sample of 100 women is taken to test if women’s mean height today is different from 1990. The mean height of the 100 surveyed women is 63.9 ...
*Monday, December 16, 2013 at 10:13pm*

**Statistics 4**

The manufacturer of Porshe 918 Spyder car claims that their car can go from 0 mph to 60 mph speed in less than 2.5 seconds. To test this claim, a sample of 40 new cars of this type were driven and their average 0-60 mph time was 2.6 seconds with a standard deviation of 0.5 ...
*Monday, December 16, 2013 at 9:42pm*

**statistics**

The breaking strength (in pounds) of a certain new synthetic is normally distributed, with a mean of 135 and a variance of 16. The material is considered defective if the breaking strength is less than 126.2 pounds. What is the probability that a single, randomly selected ...
*Monday, December 16, 2013 at 9:39pm*

**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 ...
*Monday, December 16, 2013 at 9:38pm*

**statistics**

I have done an entire project based on football scores from a certain team over the last 3 years and I'm not sure what information I can get from my answers. Ive done a frequency distribution table, Ogive, Histogram,cumulative frequency table, frequency polygon, etc. and I...
*Monday, December 16, 2013 at 7:54pm*

**statistics-PLEASE HELP quick**

I understand most of the formulas however Im not sure what the answers tell me. I did a frequency distribution table for all points scored by a football team over 4 years, but I don't understand what my answers mean and I don't want to look stupid in front of my class...
*Monday, December 16, 2013 at 7:47pm*

**Statistics**

Note: For the second problem, we use the normal approximation to the binomial distribution when finding the mean and standard deviation.
*Monday, December 16, 2013 at 6:48pm*

**Statistics**

Use z-scores. First problem: z = (x - mean)/(sd/√n) Find two z-scores: z = (2.4 - 2.5)/(0.2/√50) = ? z = (2.8 - 2.5)/(0.2/√50) = ? Finish the calculations. Next, check a z-table to find the probability between the two scores. Find mean and standard deviation...
*Monday, December 16, 2013 at 6:46pm*

**Statistics 2**

Formulas: CI90 = mean ± 1.645 (sd/√n) CI95 = mean ± 1.96 (sd/√n) For the first part, substitute the mean, standard deviation, and sample size into the appropriate formulas to determine the confidence intervals. This will help you answer the questions ...
*Monday, December 16, 2013 at 6:32pm*

**statistics in psychology**

Using an online calculator, we have 4 data pairs (x,y): (1,10) (1,8) (2,4) (4,-2) Regression equation: y = a + bx y = 12.3 - 3.67x This is the line of best fit. You can plot the scatter graph using the points above (x,y) to see how close the points are to the regression line...
*Monday, December 16, 2013 at 6:23pm*

**statistics in psychology**

12. Four research participants take a test of manual dexterity (high scores mean better dexterity) and an anxiety test (high scores mean more anxiety). The scores are as follows. Person Dexterity Anxiety 1 1 10 2 1 8 3 2 4 4 4 –2 (a) Scatter Graph: Scatter and Regression
*Monday, December 16, 2013 at 3:40pm*

**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 ...
*Monday, December 16, 2013 at 1:21pm*

**Statistics **

A manufacturing facility produces iron rods whose mean diameter is 2.5 inches with a standard deviation of 0.2 inch. If a sample of 50 metal rods produced by the facility were randomly selected, what is the probability that the mean of these rods will lie between 2.4 inches ...
*Monday, December 16, 2013 at 12:53pm*

**Statistics**

I will start it for you. Most numbers can be obtained in more than one way. 2 and 12, the only no pay numbers, can only be obtained one way. 3 = 2,1 or 1,2 = 2 ways 4 = 2,2 or 3,1 or 1,3 = 3 ways 5 = 3,2 or 2,3 or 1,4 or 4,1 = 4 ways etc.
*Monday, December 16, 2013 at 12:31pm*

**statistics**

No, unless you have more data that was not posted.
*Monday, December 16, 2013 at 12:03pm*

**Statistics**

You are so welcome
*Sunday, December 15, 2013 at 6:21pm*

**Statistics**

thank you!
*Sunday, December 15, 2013 at 6:19pm*

**Statistics**

Yes
*Sunday, December 15, 2013 at 6:18pm*

**Statistics**

so would it be true?
*Sunday, December 15, 2013 at 6:15pm*

**Statistics**

The null hypothesis will be that all population means are equal, the alternative hypothesis is that at least one mean is different.
*Sunday, December 15, 2013 at 6:10pm*

**Statistics**

True or False: For ANOVA you will reject the null hypothesis is the variability within a sample is greater than the variability among samples?
*Sunday, December 15, 2013 at 6:02pm*

**statistics**

3. Assuming α = 0.05 and that the population is normally distributed, is there enough evidence to support a claim that the mean amount of servings teenage females drink is less than or equal to 1.5 servings per day?
*Saturday, December 14, 2013 at 7:57pm*

**Statistics**

In a game you roll two fair dice. If the sum of the two numbers obtained is 3,4,9,10 or 11 you win $20. If the sum is 5,6,7 or 8 you pay $20. However if the scores on the dice are the same no one is required to pay. (a) Construct a probability distribution table for the event...
*Saturday, December 14, 2013 at 4:30pm*

**Statistics**

I assume this is for a distribution of means. Z = (score-mean)/SEm SEm = SD/√n Plug in data and solve for Z.
*Saturday, December 14, 2013 at 12:11pm*

**statistic**

Sometimes we can answer specific questions if a math or engineering or economics or science teacher is around who does statistics.
*Friday, December 13, 2013 at 9:44pm*

**statistics**

9. Explain the transformation needed to convert the following data to a linear data set. {(1, 0.98), (2, 1.39), (3, 1.71), (4, 1.98), (5, 2.22), (6, 2.43)} (6 points)
*Friday, December 13, 2013 at 7:15pm*

**Statistics**

For a population with a mean of µ=60 and standard deviation of Ợ=24, find the z=score corresponding to each of the following samples a. M=63 for sample of n=16 scores b. M=63 for sample of n=36 scores c. M=63 for sample of n=64 scores
*Friday, December 13, 2013 at 7:12pm*

**Statistics**

is this statement true or false.
*Friday, December 13, 2013 at 6:42pm*

**statistics**

Variance =38.2
*Friday, December 13, 2013 at 6:26pm*

**statistics**

what is the variance of 18, 16, 12, 2, 11
*Friday, December 13, 2013 at 6:12pm*

**Statistics (?)**

What is your question?
*Friday, December 13, 2013 at 1:29pm*

**Statistics**

SEm = SD/√n From this equation, you can see why it is false.
*Friday, December 13, 2013 at 1:29pm*

**Statistics**

Standard deviation (SD) = square root of variance 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 (.05) related to the Z score. Insert the values into ...
*Friday, December 13, 2013 at 12:44pm*

**Stats**

Z = (score-mean)/SEm SEm = SD/√n Assuming a normal distribution, find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability (.05) and its Z score. Insert Z score and other data into...
*Friday, December 13, 2013 at 12:29pm*

**Statistics**

Thank you for all your help.
*Friday, December 13, 2013 at 10:22am*

**Statistics**

86.2? :D
*Friday, December 13, 2013 at 4:06am*

**Statistics**

Scores on a certain exam are normally distributed with a mean of 78 and a variance of 25. What is the score obtained by the top 5% of the students? I do not understand the 5% part. What does the tail look like on the bell-shaped graph?
*Friday, December 13, 2013 at 4:03am*

**Statistics**

n1-25, n2-36, s1 power 2=50, s2 2 power=72, m1=100. m2=105
*Thursday, December 12, 2013 at 11:35pm*

**Statistics**

As sample size increases, the value of the standard error also increases. Ans false
*Thursday, December 12, 2013 at 10:28pm*

**mah statistics**

Mean = 0(.5) + 1(.12) + 2( .23) + 3(.3) + 46.16) + 5(.1) +5 (.04) = ? variance = 0^2(.5) + 1^2(.12) + 2^2 (.23) + 3^2(.3) + 4^2(.16) +5^2 (.1) + 5^2(.04) = ? Standard deviation = sqrt(variance -mean ^2))
*Thursday, December 12, 2013 at 10:21pm*

**Statistics**

True or False The mean for a sample of n = 4 scores has a standard error of 5 points. This sample was selected from a population with a standard deviation of ƒã = 20.
*Thursday, December 12, 2013 at 10:19pm*

**Statistics**

True or False As sample size increases, the value of the standard error also increases.
*Thursday, December 12, 2013 at 10:18pm*

**mah statistics**

the following table gives the number of camcorders sold on a given day in an electronics store X: 0, 1, 2, 3, 4, 5, 5, P(x) 0.5, .12, .23, .3, .16, .1, .04 find the mean, variance, and standard deviation of the daily sales of camcorders in the store.
*Thursday, December 12, 2013 at 6:52pm*

**Statistics**

The sample size reduces variability of distribution of means as it gets larger, but does not effect the expected value for the sample mean.
*Thursday, December 12, 2013 at 3:16pm*

**Statistics**

Using P ≤ .05, if the probability the results would occur by chance is P > .05, you would accept the null hypothesis. By using any level of significance, if it equals or is less than that level, you would be assuming that the results indicate significant differences. ...
*Thursday, December 12, 2013 at 3:11pm*

**Statistics**

a) Use ratio and proportion... 500 tagged birds/n total birds = 20/215 by cross products: 20n = 500 * 215 20n = 107,500 n = 107,500 / 20 = 5,375 b) ? c) In early spring the recently hatched baby birds are probably not available for capture, as they are still in the nest. ...
*Thursday, December 12, 2013 at 2:35pm*

**Statistics**

How is the rejection region defined and how is that related to the z-score and the p value? When do you reject or fail to reject the null hypothesis? Why do you think statisticians are asked to complete hypothesis testing? Can you think of examples in courts, in medicine, or ...
*Thursday, December 12, 2013 at 12:16am*

**Statistics**

Can someone help me do this problem? A group of environmentalist are trying to estimate the population of the state rid in clear view park. They capture a sample of 500 birds in early spring and tag them. in august they capture 215 birds, of which 20 are tagged. a) use the ...
*Thursday, December 12, 2013 at 12:12am*

**Statistics**

True or False According to the central limit theorem, the expected value for a sample mean becomes smaller, approaching zero, as the sample size approaches infinity.
*Wednesday, December 11, 2013 at 9:39pm*

**Statistics**

True or False In order for the distribution of sample means to be normal, it must be based on samples of at least n = 30 scores.
*Wednesday, December 11, 2013 at 9:39pm*

**Statistics**

Thank you for the help.
*Wednesday, December 11, 2013 at 9:36pm*

**statistics**

Victor or Junior, did you multiply my response to find the answer?
*Tuesday, December 10, 2013 at 4:25pm*

**Statistics**

Formula: z = (x - mean)/(sd/√n) With your data: z = (76 - 70)/(18/√9) = 6/6 = 1 Choice: c
*Tuesday, December 10, 2013 at 3:49pm*

**Statistics**

False. Should read "...the sampling distribution of the mean will be equal to the population mean." (Central Limit Theorem)
*Tuesday, December 10, 2013 at 3:45pm*

**STATISTICS**

How about a? Check this.
*Tuesday, December 10, 2013 at 2:59pm*

**Math :)**

first, check the differences: 8.6 2.0 1.6 2.8 1.3 Doesn't look good, since there's no obvious slope. Is this a class in statistics, where you cover linear regression? The 62.5 looks like an outlier.
*Tuesday, December 10, 2013 at 12:10pm*

**Statistics**

well, 3/4 of the scores were below 69. That leaves 1/4 above. What's 1/4 of 135?
*Tuesday, December 10, 2013 at 11:54am*

**Statistics**

Multiple choice question that's hard to figure out and understand.(information provided) Ten members of a fraternity take a statistics course. Here are their scores on the first exam in the course: 61,74,47,60,62,63,65,79,55,85. The question states: In all, 135 students ...
*Tuesday, December 10, 2013 at 11:52am*

**statistics**

Multiple choice question that's hard to figure out and understand.(information provided) Ten members of a fraternity take a statistics course. Here are their scores on the first exam in the course: 61,74,47,60,62,63,65,79,55,85. The question states: In all, 135 students ...
*Tuesday, December 10, 2013 at 11:51am*

**statistics**

You have a lot of unnecessary data given to answer your question. .25 * 135 = ?
*Tuesday, December 10, 2013 at 10:03am*

**Statistics**

disjoint
*Monday, December 9, 2013 at 10:05pm*

**Business Math and Statistics**

Ill be concise:60% of people in survey had income greater than 25k, 40% under 25k. Further, same survey, 70% have exactly 2 cars, while 30% have a different number than 2. The probability that the residents own 2 cars IF income is over 25k is 80%. what is the probability of a ...
*Monday, December 9, 2013 at 9:46pm*

**statistics**

Ten members of a fraternity take a statistics course. Here are their scores on the first exam in the course. 61,74,47,60,62,63,65,79,55,85. In all 135 students took the exam. The third quartile for all 135 scores was 69. How many students had scores higher than 69?
*Monday, December 9, 2013 at 9:17pm*

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