1. A consulting agency was asked by a large insurance company to investigate whether salespersons with businessmajors were better salespersons than those with other majors. A sample of 40 salespersons with business degreeshowed that they sold an average of 11 insurance policies per week with a standard deviation of 1.80 policies.Another sample of 45 salespersons with degree other than business showed that they sold an average of 9 insurancepolicies per week with a standard deviation of 1.35 policies.Construct a 95% confidence interval for the difference between the twopopulation means.

Given n1=sample size 1 =40, n2=sample size 2=45, sample mean 1 x̄1=11, sample mean x̄2=9, s1=sample…

Answered: 1. A consulting agency was asked by a…

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.
K.Brew sells a wide variety of outdoor equipment and clothing. The company sells both through mail order and via the internet. Random samples of sales receipts were studied for mail order sales and internet sales, with the total purchase being recorded for each sale. A random sample of 18 sales receipts for mail order sales results in a mean sale amount of $81.30 with a standard deviation of $16.25 . A random sample of 9 sales receipts for internet sales results in a mean sale amount of $67.00 with a standard deviation of $15.25 . Using this data, find the 98% confidence interval for the true mean difference between the mean amount of mail order purchases and the mean amount of internet purchases. Assume that the population variances are not equal and that the two populations are normally distributed. Step 2 of 3 : Find the standard error of the sampling distribution to be used in constructing the confidence interval. Round your answer to two decimal places.
Carlos and Devon both accepted new jobs at different companies. Carlos's starting salary is $32,000 and Devon's starting salary is $33,000. They are curious to know who has a better starting salary when compared to the salary distributions of their new employers. A website that collects salary information from a sample of employees for a number of major employers reports that Carlos's company offers a mean salary of $54,000 with a standard deviation of $6,000. Devon's company offers a mean salary of $44,000 with a standard deviation of $4,000. Find the z-scores corresponding to each of their starting salaries. Round to two decimal places, if necessary
2. Workers in a large service industry have an average wage of $13.00 per hour with a standard deviation of $0.50. The industry has 64 workers of certain ethnic group. These workers have an average wage of $12.80 per hour. Is it reasonable to assume that the wage rate of the ethnic group is equivalent to that of a random sample of workers from those employees in the service industry?
Salvatore, as the director of a regional bank, is concerned about the wait times of customers at the four branches. He randomly selects 48 patrons at each branch and records the waiting time for each patron. The results of the samples are shown below. The Alvrine branch has a mean waiting time of 13.49 minutes with a standard deviation of 1.97 minutes.The Durham branch has a mean waiting time of 12.61 minutes with a standard deviation of 2.89 minutes.The Hanover branch has a mean waiting time of 11.06 minutes with a standard deviation of 2.46 minutes.The Mascomonet branch has a mean waiting time of 12.89 minutes with a standard deviation of 3.12 minutes.
A cell phone company offers contract phones and non-contract phones. In a sample of 40 contract subscribers, the mean yearly income was found to be $57,000 with a standard deviation of $9,200. In a sample of 30 non-contract phones, the mean yearly income was found to be $53,000 with a standard deviation of $7,100. At the 1% significance level, is there evidence that the mean annual income level between the two groups is the same? Include a p-value with your test.
Assume a media agency reports that it takes television streaming service subscribers in the U.S. an average of 6.14 days to watch the entire first season of a television series, with a standard deviation of 4.03 days. Scarlett is an analyst for an online television and movie streaming service company that targets to the 18-50 age bracket. She wants to determine if her company's customers exhibit shorter viewing rates for their series offerings. Scarlett plans to conduct a one-sample z-test, with significance level of a = 0.05, to test the null hypothesis, Ho: u = 6.14 days, against the alternative hypothesis, Hj: µ < 6.14 days. The variable u is the mean amount of time, in days, that it takes for customers to watch the first season of a television series. Scarlett selects a simple random sample of 825 customers who watched the first season of a television series from the company database of over 25,000 customers that qualified. She compiles the summary statistics shown in the table.…
3. A business consultant wanted to investigate if providing day care facilities on premises by companies reduces the absentee rate of working mothers from companies that provide day care facilities on premises. Sample of 50 mothers selected from the companies that provide day care facilities was taken. These mothers missed an average of 6.4 days from work last year with a standard deviation of 1.20 days. Another sample of 50 such mothers taken from companies that do not provide day care facilities on premises showed that these mothers missed an average of 9.3 days last year with a standard deviation of 1.83 days. Construct a 98 % confidence interval for the difference between the two population means.
1. The fuel efficiency of a new model pick-up truck (truck) is measured in miles per gallon (mpg). A company claims that their new truck gets 25 mpg on average. A consumer group thinks the company is lying and claims that the mean mileage for all the trucks is less than 25 mpg. In a random sample, of forty-five of these trucks the mean mpg was 23.3 mpg with a standard deviation of 5.1 mpg. a. Conduct a hypothesis test to test the consumer group's claim at the 5% significance level. Be sure to state you Ho and Ha, your test statistic and p- value, whether or not you reject Ho and whether you support the claim. b. Write a complete sentence describing what a Type I error is in context. c. Write a complete sentence describing what a Type II error is in context.
5. The heights of a pediatricians three-year-old females are approximately normally distributed, with mean 38.72 inches and standard deviation 3.17 inches. Find the height of a three-year-old female at the 42nd percentile.
2. In a study of inter spousal aggression and its possible effect on child behavior, the Behavior Problem Checklist (BPC) scores were recorded for 47 children and whose parents were classified as aggressive. The sample mean and standard deviation were 7.92 and 3.45, respectively. For a sample of 38 children whose parents were classified as non-aggressive, the mean and standard deviation of the BPC scores were 5.80 and 2.87, respectively. Do these observations substantiate the conjecture that the children of aggressive families have higher mean BPC than those of non-aggressive families? Use a significance level of 0.05. 3. Ms Julia Palac is an instructor in Statistics. She gave an examination before and after he discussed the topic "hypothesis testing" and gathered the following data: Studen Score before Score after Discussion Discussion 81 85 87 90 70 75 4 89 93 85 88 At a = 0.01 level of significance, is the learning effective?
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…

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