Friday

April 18, 2014

April 18, 2014

**Recent Homework Questions About Statistics**

Post a New Question | Current Questions

**math**

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, November 30, 2013 at 4:26pm*

**statistics**

what test are you using? This is very confusing!
*Saturday, November 30, 2013 at 1:20pm*

**statistics**

Z = (mean1 - mean2)/standard error (SE) of difference between means SEdiff = √(SEmean1^2 + SEmean2^2) SEm = SD/√n (n = # of trips) If only one SD is provided, you can use just that to determine SEdiff. Find table in the back of your statistics text labeled ...
*Saturday, November 30, 2013 at 12:53pm*

**statistics**

Ala rge fleet of cars is maintained with an average of 26 mpg. 50 recent trips displayed a mean of 25.02 mpg and standard deviation of 4.1 mpg. At the 5% level of significance, is their evidence the company has failed to keep their fuel goals? I did the math and got .03380315...
*Saturday, November 30, 2013 at 12:27pm*

**Statistics**

a
*Saturday, November 30, 2013 at 10:23am*

**Probability and Statistics**

The proportion of adults living in a small town who are college graduates is estimated to be p = 0.6. To test this hypothesis, a random sample of 15 adults is selected. If the number of college graduates in the sample is anywhere from 6 to 12, we shall not reject the null ...
*Saturday, November 30, 2013 at 1:50am*

**Statistics**

Thank you, I got the same answer, but I thought that because the sample size was less than 30, there was something I missed.
*Friday, November 29, 2013 at 11:30pm*

**Statistics**

mean = $115 Sd = $25 n = 15 1-a = .92 a = 0.08 Za/2 = z.04 = 1.75 115 -+ 1.75 * 25/sqrt15)) 115-+ 11.296 (103.704, 126.296)
*Friday, November 29, 2013 at 11:25pm*

**Statistics**

I have two coins: a quarter and a nickel. The quarter has a bias of 1/4 for heads, and the nickel has a bias of 2/3 for heads. I flip each coin 10 times. What is the probability that I observe exactly five heads total? Some explanation of the solution would be appreciated.
*Friday, November 29, 2013 at 11:04pm*

**Statistics**

Hello, my problem is I have a random sample of only 15 sales average is $115 with a known population standard deviation of $25.00. Obtain a 92% confidence interval and explain what your answer means. I am not sure what to do because the sample size is only 15. Thanks for your ...
*Friday, November 29, 2013 at 8:00pm*

**Probability and Statistics**

The proportion of adults living in a small town who are college graduates is estimated to be p = 0.6. To test this hypothesis, a random sample of 15 adults is selected. If the number of college graduates in the sample is anywhere from 6 to 12, we shall not reject the null ...
*Friday, November 29, 2013 at 7:30pm*

**statistics**

raw numbers
*Friday, November 29, 2013 at 8:55am*

**statistics**

In a distribution of sentence lengths in months like the following: 6, 12, 10, 18, 24, 360; which statistic would a researcher not want to report? a. standard deviation b. mean c. range d. raw numbers
*Friday, November 29, 2013 at 8:13am*

**Probability and Statistics**

The proportion of adults living in a small town who are college graduates is estimated to be p = 0.6. To test this hypothesis, a random sample of 15 adults is selected. If the number of college graduates in the sample is anywhere from 6 to 12, we shall not reject the null ...
*Thursday, November 28, 2013 at 5:13pm*

**Probability and Statistics**

The proportion of adults living in a small town who are college graduates is estimated to be p = 0.6. To test this hypothesis, a random sample of 15 adults is selected. If the number of college graduates in the sample is anywhere from 6 to 12, we shall not reject the null ...
*Wednesday, November 27, 2013 at 11:34pm*

**Statistics**

KE$HA IS A CELEB. I LOVE HER I LOV EHER KE$HIE IS A CELEB I LOVE HER_♥__♥_____♥__♥;___ Put This _♥_____♥_♥_____♥__ Heart _♥______♥______♥__ On Your __♥_____/______♥__ Page If ___♥...
*Wednesday, November 27, 2013 at 1:14pm*

**Math**

I'm currently taking IBMS and it has elements of several types of math classes (calculus, statistics, algebra, etc.). It is the "lowest" level IB Math class one can take, but not necessarily for students who have a low background in math. I know one student who ...
*Wednesday, November 27, 2013 at 10:45am*

**Statistics**

well, since 51.75 is 57.5% of the way between 46 and 56, ...
*Wednesday, November 27, 2013 at 6:05am*

**Statistics**

A statistics professor plans her classes so carefully that the lengths of her class are uniformly distributed between 46.0 and 56.0 minutes. Find the probablity that given class period runs less than 51.75 minutes
*Wednesday, November 27, 2013 at 3:47am*

**Statistics**

a. Ho: p = 0.5 Ha: p > 0.5 b) z = 2.41 c) p-value = 0.0080 d) reject the Ho; there is sufficient evidence to claim that the probability of a baby being a girl is greater than 0.5
*Tuesday, November 26, 2013 at 6:27pm*

**Statistics**

A clinical trial tests a method designed to increase the probability of conceiving a girl. In the study, 449 babies were born, and 250 of them were girls. Use the sample data with .01 significance level to test the claim that with this method, the probability of a baby being a...
*Tuesday, November 26, 2013 at 6:03pm*

**statistics**

A few hints: If you use the normal distribution as an approximation, then you will need to find the mean and standard deviation. mean = np = 13 * 0.7 = 9.1 standard deviation = √npq = √(13)(0.7)(0.3) = 1.65 (rounded) Note: q = 1 - p Next step: use z-scores z = (x...
*Tuesday, November 26, 2013 at 4:41pm*

**statistics**

The result is a statistic because it describes some characteristics of a sample. Or is it because if describes some characteristics of a population? this is where I get confused. thanks
*Tuesday, November 26, 2013 at 1:37pm*

**statistics**

A parameter is data about the whole population, while a statistic deals with a part of the population, a sample. What does that tell you?
*Tuesday, November 26, 2013 at 1:16pm*

**statistics**

A particular country has 55 total states. If the areas of 30 states are added and the sum is divided by 30, the result is 196,582 square kilometers. Determine whether this result is a statistic or a parameter and why.
*Tuesday, November 26, 2013 at 1:02pm*

**statistics**

With n=13 and p= 0.7, find the binomial probability p(9) by using a binomial probability table. If np> and nq> 5, also estimate the indicated probability by using the normal distribution as an approximation to the binomial, if np<5 or nq<5 then state that the ...
*Monday, November 25, 2013 at 9:36pm*

**statistics**

See your other post.
*Monday, November 25, 2013 at 7:24pm*

**statistics**

Outliers in a box plot may be evidence of a non-normal distribution, but this might not always be the case. If the box plot has symmetry around the median, the distribution will most likely be normal.
*Monday, November 25, 2013 at 7:23pm*

**Statistics**

It may be due to the sample size. There is a possibility the sample may be too large, which will affect the significance of the outcome.
*Monday, November 25, 2013 at 6:51pm*

**statistics**

You can try a proportional one-sample z-test for this one since this problem is using proportions. Here's a few hints to get you started: Null hypothesis: Ho: p = .5 -->meaning: population proportion is equal to .5 Alternative hypothesis: Ha: p > .5 -->meaning: ...
*Monday, November 25, 2013 at 6:36pm*

**statistics**

If you need to show the work by hand, you can develop the regression equation in the following format: predicted y = a + bx ...where a represents the y-intercept and b the slope. To get to that point, here are some formulas to calculate along the way. To find a: a = (Ey/n) - b...
*Monday, November 25, 2013 at 6:25pm*

**Statistics**

If you perform a statistical test, try a one-sample z-test. z = (sample mean - population mean)/(standard deviation divided by the square root of the sample size) Population mean = 80 Sample mean = ? (I don't see one listed) Standard deviation = 10.15 Sample size = 50 Once...
*Monday, November 25, 2013 at 6:19pm*

**Statistics**

An industrial psychologist has a stress test that is used to determine the amount of stress that managers are under. A value of 80 or higher indicates “high stress.” The industrial psychologist believes that the managers at a large, profitable pharmaceutical firm are...
*Monday, November 25, 2013 at 5:22pm*

**statistics**

In a study of caffeine and stress, college students indicate how many cups of coffee they drink per day and their stress level on a scale of 1-10. The data appear below. Number of Cups of Coffee Stress Level 3 5 2 3 4 3 6 9 5 4 1 2 7 10 3 5 = 3.88 X= 5.13 s = 2.03 s = 2.90 ...
*Monday, November 25, 2013 at 3:36pm*

**statistics**

right.
*Monday, November 25, 2013 at 1:26pm*

**Statistics**

% = mean ± Z(SEm) Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability (%/2) from the mean and its Z score. Substitute values into above equation and calculate. If you ...
*Monday, November 25, 2013 at 1:23pm*

**statistics**

A normal distribution approximates a bell-shaped curve. Outliers to one side would skew the distribution. If the distribution was flat, having about the same frequencies throughout the distribution, this would be non-normal. Also a bimodal distribution would be non-normal, ...
*Monday, November 25, 2013 at 1:17pm*

**statistics psy/315**

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 "...
*Monday, November 25, 2013 at 1:02pm*

**statistics psy/315**

Based on the information given for each of the following studies, decide whether to reject the null hypothesis.For each, give (a) the Z-score cutoff (or cutoffs) on the comparison distribution at which the null hypothesis should be rejected(b) the Z score on the comparison ...
*Monday, November 25, 2013 at 11:12am*

**statistics**

A clinical trial tests a method designed to increase the probability of conceiving a girl. In a study 306 babies were born, and 174 of them were girls. the sample data with a 0.01 significance level to test the claim that with this method, the probability of being a girl is ...
*Monday, November 25, 2013 at 10:25am*

**Statistics**

n two separate studies, the actual difference between the means of a treated group and an untreated group is 3 points. However, in one study, the ÏƒM1-M2 is very large and so the 3 points is not found to be significant. In the other study, the ÏƒM1-M2 is ...
*Monday, November 25, 2013 at 7:18am*

**Statistics**

(1.96*2.5)/0.25)^2=384.16 that's right or wrong?? i'm not understand why the population standard deviation round up to 3?? anyone help? this for question post by shyra..
*Monday, November 25, 2013 at 1:27am*

**statistics**

how would you tell deviations from normality by looking at a box plot?
*Sunday, November 24, 2013 at 7:11pm*

**statistics**

how would you tell deviations from normality by looking at a box plot?
*Sunday, November 24, 2013 at 7:08pm*

**statistics**

what makes a probability plot non-normal? I would think outliers are one of them, but what else?
*Sunday, November 24, 2013 at 7:06pm*

**Statistics**

Given the following information, determine the 68.3 percent, 95.5 percent, and 99.7 percent confidence intervals. overbar above X equals 4.33 comma SE sub m equals 3 I would appreciate it extremely if someone would help me figure this out. I honestly have no idea how to do ...
*Sunday, November 24, 2013 at 6:33pm*

**statistics**

I think I have it...nevermind .94 on z chart =1.55...then multiply 1.55 times error (10) then time 60=75.5?
*Sunday, November 24, 2013 at 5:26pm*

**statistics**

Typing speeds among college students are normally distributed with a mean of 60 words, and a standard deviation of 10 words. determine the typing speed that separates the top 6% typists from the rest.
*Sunday, November 24, 2013 at 3:55pm*

**statistics**

1. A professor measured the time (in seconds) required to catch a falling meter stick for 19 randomly selected students’ dominant and non-dominant hand. The professor claims that the reaction time in an individual’s dominant hand is less than the reaction time in ...
*Sunday, November 24, 2013 at 3:33pm*

**Statistics**

I get it now...I was missing a step too! Thanks Much!
*Sunday, November 24, 2013 at 3:23pm*

**Statistics**

YES. IF YOUR PROFESSOR SAID THAT YOUR ANSWER SHOULD BE IN PERCENT. P = 142/507 = 0.28 SD = SQRT( .28*.72/507) SQRT(0.2016/507) = 0.0199 1-a = .95 a =0.05 za/2 = z0.025 = 1.96 Z = 1.96 p -+ za/2 * SD/sqrt(n) 0.28-+1.96*0.0199 0.28-+ 0.039 ( 0.241, 0.319) IF YOUR PROFESSOR SAID...
*Sunday, November 24, 2013 at 3:22pm*

**Statistics**

YES. IF YOUR PROFESSOR SAID THAT YOUR ANSWER SHOULD BE IN PERCENT. P = 142/507 = 0.28 SD = SQRT( .28*.72/507) SQRT(0.2016/507) = 0.0199 Z = 1.96 0.28-+1.96*0.0199 0.28-+ 0.039 ( 0.241, 0.319)
*Sunday, November 24, 2013 at 3:13pm*

**Statistics**

142 out of 507 people were right. Calculate a 95% confidence interval for the proportion of the entire population that could be right. I did some of the work …Please help. I am getting .0199 SD =sqt(.28(1-.28)/506 = .0119 so .28 +/- .0119 so I could say that with 95% ...
*Sunday, November 24, 2013 at 3:08pm*

**Statistics**

you know I am getting .0199 SD =srt(.28(1-.28)/506 = .0119? Please check for me again?
*Sunday, November 24, 2013 at 2:56pm*

**Statistics**

so I could say that with 95% confidence, between 24.1% and 31.9% of the entire population could be right?
*Sunday, November 24, 2013 at 2:27pm*

**statistics (?)**

What following? 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 related to the Z score. This may help you decide.
*Sunday, November 24, 2013 at 2:04pm*

**Statistics**

p = 142/ 507 = 0.28 SD = sqrt(p(1-p)/n) 0.28-+ 0.039 (.241, .319)
*Sunday, November 24, 2013 at 2:00pm*

**Statistics**

a) 1.409 b) ( -2.822, 5.64) c) 4.23
*Sunday, November 24, 2013 at 1:52pm*

**Statistics**

142 out of 507 people were right. Calculate a 95% confidence interval for the proportion of the entire population that could be right. I did some of the work and got .72...don't know what to do with this? Please help.
*Sunday, November 24, 2013 at 1:45pm*

**Statistics**

A sample of 11 observations taken from a normally distributed population produced the following data. −7.1 10.3 8.7 −3.6 −6.0 −7.5 5.2 3.7 9.8 −4.4 6.4 a) What is the point estimate of μ? b) Make a 95% confidence interval for μ. c) What ...
*Sunday, November 24, 2013 at 12:25pm*

**Statistics**

Many dairy cows now receive injections of BST, a hormone intended to spur greater milk production. A group of 53 Jersey cows increased average milk production from 43 to 52 pounds per day, with a standard deviation of 4.8 lbs. Is this evidence that the hormone maybe effective ...
*Sunday, November 24, 2013 at 9:14am*

**statistics**

For the past 20 years, the high temperature on April 15th has averaged = 62 degrees with a standard deviation of = 12. Last year, the high temperature was 68 degrees. Based on this information, which of the following best describes last year's temperature...
*Sunday, November 24, 2013 at 2:42am*

**Statistics**

Margin of error = 0.02 z = 2.58 Unknown p We are going use 50% n = (za/2 /E ) ^2 *p(1-p) n = (2.58/0.02)^2*.5* .5 = 4160.25 n = 4161
*Saturday, November 23, 2013 at 7:16pm*

**Statistics**

Margin of error = 0.02 z = 2.58 Unknown p We are going use 50% n = (za/2 /E ) ^2 *p(1-p) n = (2.58/0.02)^2*.5* .5 = 4160.25 n = 4161
*Saturday, November 23, 2013 at 7:16pm*

**Statistics**

This is not correct
*Saturday, November 23, 2013 at 6:41pm*

**Statistics**

4065
*Saturday, November 23, 2013 at 6:13pm*

**Statistics**

Exercise 8.92 Tony's Pizza guarantees all pizza deliveries within 30 minutes of the placement of orders. An agency wants to estimate the proportion of all pizzas delivered within 30 minutes by Tony's. What is the most conservative estimate of the sample size that would...
*Saturday, November 23, 2013 at 6:10pm*

**Statistics**

Tony's Pizza guarantees all pizza deliveries within 30 minutes of the placement of orders. An agency wants to estimate the proportion of all pizzas delivered within 30 minutes by Tony's. What is the most conservative estimate of the sample size that would limit the ...
*Saturday, November 23, 2013 at 6:08pm*

**statistics**

10.9 - +2.575 *6.2/√300 10-+ 0.9217 = (9.98, 11.82)
*Saturday, November 23, 2013 at 4:06pm*

**Statistics**

Use. Population proportion Ho: p = 0.2 Ha: p > 0.2 if P-value is greater than significance level fail to reject Ho: if P-value is less than significance level Reject Ho. z = 2.80 p-value = p ( z > 2.8) = 0.003 Reject the null hypothesis. There is sufficient evidence ...
*Saturday, November 23, 2013 at 3:59pm*

**statistics**

If the average commute time is 10.9 miles, but the average is actually the mean of a sample of 300 commuters and the sample standard deviation is 6.2 miles Estimate the true mean commute distance using 99% confidence level.
*Saturday, November 23, 2013 at 3:00pm*

**Statistics**

125/500 women soda drinkers indicate they drink diet soda. At the .01 level, does this evidence indicate that more than 20% of the women soda drinkers drink diet soda? Determine and explain the P-value please. I have the numbers...just cannot explain. Please help.
*Saturday, November 23, 2013 at 2:51pm*

**statistics**

Cannot sketch on these posts. Z = (score-mean)/SD Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportions/probabilities related to the Z scores.
*Saturday, November 23, 2013 at 12:57pm*

**statistics**

Type I: rejecting Ho when it is true Type II: failure to reject Ho when it is false answer is false
*Saturday, November 23, 2013 at 11:01am*

**statistics**

Failing to reject the null hypothesis when it is false is a Type II Error. T or F, and why or why not?
*Saturday, November 23, 2013 at 10:30am*

**statistics**

IQ scores were obtained from randomly selected couples.For 20 such pairs of people, the linear correlation coefficient is 0.881 and the equation of the regression line is y= -6.93+ 10.8x, where x represents the IQ score of the husband. Also, the 20x values have a mean of 105....
*Saturday, November 23, 2013 at 8:42am*

**statistics**

Assume that thermometer readings are normally distributed with a mean of 0.0 and a standard deviation of 1,00. the thermometer is randomly selected and tested. For the case below, draw a sketch , and find the probability of the reading The given values in Celsius degrees) ...
*Friday, November 22, 2013 at 2:09pm*

**Statistics**

Right
*Friday, November 22, 2013 at 12:30pm*

**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 "...
*Friday, November 22, 2013 at 12:29pm*

**statistics (?)**

Where is your data?
*Friday, November 22, 2013 at 12:21pm*

**statistics**

Is there a significant difference between first year post college incomes of graduates from public versus private institutions? Provide the IV, DV, and best method of analysi
*Thursday, November 21, 2013 at 9:41pm*

**Statistics**

Many dairy cows now receive injections of BST, a hormone intended to spur greater milk production. A group of 53 Jersey cows increased average milk production from 43 to 52 pounds per day, with a standard deviation of 4.8 lbs. Is this evidence that the hormone maybe effective ...
*Thursday, November 21, 2013 at 7:31pm*

**Statistics**

If the cases selected for one sample have no influence upon the cases selected for a second sample, then the samples are said to be: A) independent B) inconsistent C) dependent D) consistent A
*Thursday, November 21, 2013 at 7:27pm*

**Statistics**

The effectiveness of a headache medicine is tested by measuring the intensity of a headache in patients before and after drug treatment. The data consist of before and after intensities for each patient. Identify the design of the study. A) Paired t-test B) Two-sample t-test C...
*Thursday, November 21, 2013 at 6:40pm*

**Statistics**

A researcher wished to test the effect of the addition of extra calcium to yogurt on the "tastiness" of yogurt. Two different yogurts, one with extra calcium and one without the added calcium, were created from the same batch of yogurt. A group of 84 adult volunteers...
*Thursday, November 21, 2013 at 6:39pm*

**statistics 201**

You can use a one-sample z-test. z = (sample mean - population mean)/(standard deviation divided by the square root of the sample size) With your data: z = (375 - 350)/(150/√100) = 25/15 = 1.67 (rounded) If you use a 5% significant level for a one-tailed test (Ha: µ...
*Thursday, November 21, 2013 at 4:50pm*

**statistics 201**

A firm hires a pool of financial consultants to discuss portfolio recommendations with its clients. The CEO believes that another financial consultant should be hired if the average phone consultation exceeds 350 seconds. A random sample of 100 phone calls revealed a mean of ...
*Thursday, November 21, 2013 at 2:48pm*

**statistics**

„« If the city spends $145,000 on promotional expenditures. What will be the projected attendance at 95% confidence level?
*Thursday, November 21, 2013 at 1:22pm*

**Statistics**

% = mean ± ? SEm Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability ([1-%]/2) and its Z score. Enter Z score for ?. Solve for intervals.
*Thursday, November 21, 2013 at 11:30am*

**Statistics**

A null hypothesis expects no difference.
*Thursday, November 21, 2013 at 11:26am*

**Statistics**

% = mean ± ? 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 ([1-%]/2) to find the Z score. Insert that into ? position. Example: 95% = 74.8 &...
*Thursday, November 21, 2013 at 11:24am*

**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...
*Thursday, November 21, 2013 at 11:11am*

**Statistics**

Given the following null hypothesis, give an example of a Type II error. Ho: There is no difference in the level of understanding of this chapter between students who have previously taken a statistics course and students who have not previously takn a stastics course.
*Thursday, November 21, 2013 at 9:55am*

**Statistics**

given the following null hypothesis, give an example of a type I error. Ho: There is no difference between the number of males or females who go to their primary care physician for an annual exam.
*Thursday, November 21, 2013 at 9:53am*

**Statistics**

given the following information, determine the 68.3 percent, 95.5 percent, and 99.7 percent confidence intervals. Mean = 4.33, standard error of the mean =3
*Thursday, November 21, 2013 at 9:46am*

**Statistics**

Create a null hypothesis for the following research questions: a. What are the differences between emergency room shifts on medication errors? b. On a clinical trial of a new drug, what will be the effects over a currently used drug?
*Thursday, November 21, 2013 at 9:41am*

**statistics**

105.88
*Thursday, November 21, 2013 at 6:51am*

**statistics**

99% confidence interval z = 2.575 p hat = 68/87 =0.7816 E= Za/2 *sqrt((phat(1-phat)/n)) E = 2.575*sqrt(0.7816*0.2184/87) E = 0.1141 phat-E < P < Phat+ E 0.7816-0.1141 <p< .7816+.1141 0.6675 < p < 0.8957
*Wednesday, November 20, 2013 at 10:02pm*

**statistics**

conduct a study on support of ban on smartphones in class. 68/87 said yes. How large of a sample is needed to be sure the margin of error +/- 3.5% with 99% confidence. I know this is estimation...but I am not sure how to go about solving this problem.
*Wednesday, November 20, 2013 at 9:38pm*

**statistics**

I am conducting a study on support of ban on smartphones in class. 68/87 said yes to the ban. How large of a sample is needed to be sure the margin of error +/- 3.5% with 99% confidence. I know this is estimation...but I am not sure how to go about solving this problem.
*Wednesday, November 20, 2013 at 9:19pm*

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