2) A study was conducted to determine if the salaries of librarians from two neighboring cities were equal. Asample of 15 librarians from each city was randomly selected. The mean from the first city was $28,900 with astandard deviation of $2300. The mean from the second city was $30,300 with a standard deviation of $2100.Construct a 95% confidence interval for- P2.

2 State the hypotheses. That is, the salaries of librarians from the two neighboring cities are…

Answered: 2) A study was conducted to determine…

MATLAB: An Introduction with Applications

6th Edition

ISBN:9781119256830

Author:Amos Gilat

Publisher:Amos Gilat

Chapter1: Starting With Matlab

Section: Chapter Questions

Problem 1P

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A pharmaceutical company needs to know if its new cholesterol drug, Praxor, is effective at lowering cholesterol levels. It believes that people who take Praxor will average a greater decrease in cholesterol level than people taking a placebo. After the experiment is complete, the researchers find that the 38 participants in the treatment group lowered their cholesterol levels by a mean of 23.2 points with a standard deviation of 4.4 points. The 44 participants in the control group lowered their cholesterol levels by a mean of 21.5 points with a standard deviation of 2.9 points. Assume that the population variances are not equal and test the company's claim at the 0.01 level. Let the treatment group be Population 1 and let the control group be Population 2. Step 2 of 3: Compute the value of the test statistic. Round your answer to three decimal places.
1a) Work Time Lost due to Accidents At a large company, the Director of Research found that the average work time lost by employees due to accidents was 97 hours per year. She used a random sample of 22 employees. The standard deviation of the sample was 5.8 hours. Estimate the population mean for the number of hours lost due to accidents for the company, using a 90% confidence interval. Assume the variable is normally distributed. Use a graphing calculator and round the answers to the nearest whole number. ___ < μ < ___ 1b) Hospital Noise Levels For a sample of 26 operating rooms taken in a hospital study, the mean noise level was 43.9 decibels, and the standard deviation was 8.9. Find the 97% confidence interval of the true mean of the noise levels in the operating rooms. Assume the variable is normally distributed. Use a graphing calculator and round the answers to at least one decimal place. ___ < μ < ___ 1c) Unhealthy Days in Cities The number of unhealthy days…
A custodian wishes to compare two competing floor waxes to decide which one is best. He believes that the mean of WaxWin is greater than the mean of WaxCo. In a random sample of 40 floors of WaxWin and 43 of WaxCo. WaxWin had a mean lifetime of 26.3 and WaxCo had a mean lifetime of 28. The population standard deviation for WaxWin is assumed to be 7.1 and the population standard deviation for WaxCo is assumed to be 6.1. Perform a hypothesis test using a significance level of 0.05 to help him decide. Let WaxWin be sample 1 and WaxCo be sample 2. The correct hypotheses are: O Ho: µ1 H2(claim) Ο H: μι μp HA: H1 < µ2(claim) O Ho: µ1 = 2 HA: μι μ (claim) Since the level of significance is 0.05 the critical value is 1.645 The test statistic is: (round to 3 places) The p-value is: (round to 3 places) The decision can be made to: O reject Ho O do not reject Ho The final conclusion is that: O There is enough evidence to reject the claim that the mean of WaxWin is greater than the mean of WaxCo.…
A researcher is attempting to calculate a 95% confidence interval for the mean average wingspan of Statsian Swallows in a particular rainforest. They take a sample and find that of the 16 swallows surveyed, the mean average was 3.14 inches and the standard deviation was 0.2 inches. What is the 95% confidence interval for this sample?
We are trying whether, a new low fat diet actually helps obese people lose weight. 100 randomly obese people are assigned to group 1 and put on a low fat-diet. another 100 people are assigned to group 2 and put on a diet of approximately the same amount of food, but not as low in fat. After 4 months, the mean net weight loss was 9.31 pounds for group 1 with a standard deviation of 4.67 pounds, and for group 2 the mean net weight loss was 7.40 pounds with a standard deviation of 4.04 pounds. Is the low-fat diet more effective? Perform a hypothesis test at the 5% significance level a) Define Parameters and state null and alternative hypothesis b) Find test statistics c) Find p-value d) Conclusion
A new drug is being tested to see if it reduces the frequency of migraines. Study participants were divided into two groups. 49 participants in group 1 received the medication; 42 participants in group 2 received a placebo. After a period of six months, group 1 had a mean of 4 migraines. It is known that the population standard deviation for this group is 1.3 migraines. Group 2 had a mean of 5.4 migraines. The population standard deviation for this group is 1.7 migraines. Can we conclude that the medication reduces the population mean number of migraines? Use αα =0.01. Note: If t-test, then unequal variances are assumed. Question a)Let: μ1μ1 = the population mean number of migraines with the medication μ2μ2 = the population mean number of migraines with the placebo (Step 1) State the null and alternative hypotheses by selecting the appropriate symbol, and identify which tailed test: H0:H0: μ1μ1 μ2μ2 H1:H1: μ1μ1 μ2μ2 Which tailed test…
Fran is training for her first marathon, and she wants to know if there is a significant difference between the mean number of miles run each week by group runners and individual runners who are training for marathons. She interviews 42 randomly selected people who train in groups and finds that they run a mean of 47.1 miles per week. Assume that the population standard deviation for group runners is known to be 4.4 miles per week. She also interviews a random sample of 47 people who train on their own and finds that they run a mean of 48.5 miles per week. Assume that the population standard deviation for people who run by themselves is 1.8 miles per week. Test the claim at the 0.01 level of significance. Let group runners training for marathons be Population 1 and let individual runners training for marathons be Population 2. Step 2 of 3 : Compute the value of the test statistic. Round your answer to two decimal places.
A new small business wants to know if its current radio advertising is effective. The owners decide to look at the mean number of customers who make a purchase in the store on days immediately following days when the radio ads are played as compared to the mean for those days following days when no radio advertisements are played. They found that for 10 days following no advertisements, the mean was 18.3 purchasing customers with a standard deviation of 1.8 customers. On 7 days following advertising, the mean was 19.4 purchasing customers with a standard deviation of 1.6 customers. Test the claim, at the 0.02 level, that the mean number of customers who make a purchase in the store is lower for days following no advertising compared to days following advertising. Assume that both populations are approximately normal and that the population variances are equal. Let days following no advertisements be Population 1 and let days following advertising be Population 2. Step 3 of 3: Draw a…
The authors of a certain paper describe a study to evaluate the effect of mobile phone use by taxi drivers in Greece. Fifty taxi drivers drove in a driving simulator where they were following a lead car. The drivers were asked to carry on a conversation on a mobile phone while driving, and the following distance (the distance between the taxi and the lead car) was recorded. The sample mean following distance was 3.40 meters and the sample standard deviation was 1.11 meters. (Use a table or technology.) (a) Construct a 95% confidence interval (in meters) for µ, the population mean following distance while talking on a mobile phone for the population of taxi drivers. (Round your answers to three decimal places.) |× ) m Interpret the interval
A pharmaceutical company needs to know if its new cholesterol drug, Praxor, is effective at lowering cholesterol levels. It believes that people who take Praxor will average a greater decrease in cholesterol level than people taking a placebo. After the experiment is complete, the researchers find that the 44 participants in the treatment group lowered their cholesterol levels by a mean of 18.7 points with a standard deviation of 3.3 points. The 39 participants in the control group lowered their cholesterol levels by a mean of 18.1 points with a standard deviation of 2.1 points. Assume that the population variances are not equal and test the company’s claim at the 0.02 level. Let the treatment group be Population 1 and let the control group be Population 2. Step 1 of 3 : State the null and alternative hypotheses for the test. Fill in the blank below. H0: μ1=μ2 Ha : μ1⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯μ2 Step 2 of 3: what is the test statistic Step 3 of 3: draw a conclusion, fail or reject. Is…
4. A fire extinguisher salesman would like to estimate the mean number of home fires started by candles each year. He obtained fire data for seven randomly selected years from the National Fire Protection Agency. His sample produced a mean of 7041 fires with a standard deviation of 1600. Create the 90% confidence interval of interest.
A pharmaceutical company needs to know if its new cholesterol drug, Praxor, is effective at lowering cholesterol levels. It believes that people who take Praxor will average a greater decrease in cholesterol level than people taking a placebo. After the experiment is complete, the researchers find that the 46 participants in the treatment group lowered their cholesterol levels by a mean of 19.5 points with a standard deviation of 4.9 points. The 37 participants in the control group lowered their cholesterol levels by a mean of 18.4 points with a standard deviation of 4.1 points. Assume that the population variances are not equal and test the company's claim at the 0.02 level. Let the treatment group be Population 1 and let the control group be Population 2. Step 2 of 3: Compute the value of the test statistic. Round your answer to three decimal places.

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