12. The manager of a fast-food restaurant wants to be sure that, on average, customers are served within 4 minutes from the time the order is placed. He is particularly concerned about the staff working during the early morning shift. From a random sample of 41 orders, the mean time was 3.75 minutes with a standard deviation of 1.2 minutes. (a) Is there convincing evidence at the a= 0.05 significance level that the true mean service time during the early morning shift is less than 4 minutes?

12. The manager of a fast-food restaurant wants to be sure that, on average, customers are served within 4 minutes from the time the order is placed. He is particularly concerned about the staff working during the early morning shift. From a random sample of 41 orders, the mean time was 3.75 minutes with a standard deviation of 1.2 minutes. (a) Is there convincing evidence at the a= 0.05 significance level that the true mean service time during the early morning shift is less than 4 minutes?

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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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3. The distribution of test scores in a class is unimodal and symmetric with a mean of 80 pts and a standard deviation of 7pts. Based on the information, Adam estimated that his score is higher than approximately 97.5% of the students in class. What score did Adam receive? Explain.
4. A medical statistician wants to estimate the average weight loss of people who are on a new diet plan. In a preliminary study, he guesses that the standard deviation of weight loss is about 10 pounds. How large a sample should he take to estimate the mean weight loss to within 2 pounds, with a 90% confidence.
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.
12. The manager of a rent-a-car business want to know whether the true average numbers of cars rented a day is 25 with a standard deviation of 6.9 rentals. A random sample of 36 days was taken and found to have an average of 22.8 rentals. Test at 0.05 level of significance. Criterion : Decision : Conclusion :
15. The Exotic Fruit Juice Co. sell cartons of Passion Fruit and Orange fruit juice. The amount of liquid in each carton is normally distributed with a mean of 266ml and a standard deviation of 20ml. Cartons containing more than 300ml produce no profit. What percentage of cartons will this be?
10. In a study conducted to determine the role that sleep disorders play in academic performance, researcher Jane Gaultney conducted a survey of 503 randomly selected students with a known sleep disorder (such as narcolepsy, insomnia, or restless leg syndrome) and found their mean GPA was 2.65 with a standard deviation of 0.87. Similarly, she randomly selected 1342 students with no known sleep disorders, and found their mean GPA to be 2.82 with a standard deviation of 0.83. You may assume that both population GPA's are normally distributed. Use a significance level of 0.05 to test whether the two groups have different mean GPA's. As a follow-up, construct and interpret a 95% confidence interval for the true difference in the mean GPA's of the two groups. What would be the type I and type II errors for this problem?
11. In a sample of 41 business trips taken by employees in the HR department, a company finds that the average amount spent for the trips was $1,441 with a standard deviation of $423. In a sample of 101 trips taken by the employees in the sales department is $1,799 with a standard deviation of $653. When testing the hypothesis (at the 10% level of significance) that the variance of the amount spent on trips taken by the sales department is higher than those taken by the HR department what is the critical value? (please round your answer to 2 decimal places)
3. An article by S. M. Berry titled “Drive for Show and Putt for Dough (Chance, Vol 12(4), pg 50-54)” discussed driving distances of PGA players. The mean distance for tee shots on the 1999 men’s PGA tour is 272.2 yards with a standard deviation of 8.12 yards. Assuming that the 1999 tee-shot distances are normally distributed, find the percentage of such tee shots that went a. between 260 and 280 yards. b. more than 300 yards. 4. Do Exercise 6.103 on page 288 in the textbook. Show work. (image attached) 5. Refer to question 3 in this homework. The article “Drive for Show and Putt for Dough (Chance, Vol 12(4), pg 50-54)” discussed driving distances of PGA players. The mean distance for tee shots on the 1999 men’s PGA tour is 272.2 yards with a standard deviation of 8.12 yards. Assuming that the 1999 tee-shot distances are normally distributed answer the following questions: a. Determine the quartiles of the driving distances b. Find the 95th percentile. c. Obtain the third decile (i.e.…
Thompson and Thompson is a steel bolts manufacturing company. Their current steel bolts have a mean diameter of 132 millimeters, and a variance of 64. If a random sample of 39 steel bolts is selected, what is the probability that the sample mean would be greater than 128.2 millimeters? Round your answer to four decimal places. Answer How to enter your answer (opens in new window) Keypad Keyboard Shortcuts Tables
1. For each day of last year, the number of vehicles passing through a certain intersection was recorded by a city engineer. One objective of this study was to determine the percentage of days that more than 425 vehicles used the intersection. If the mean data was 375 vehicles per day and the standard deviation was 25 vehicles: (c) Suppose the relative frequency distribution for the data is bell-shaped, then what percentage of days 325 and 425 vehicles used the intersection? 95% at least 75% 68% 75% between
3. A local hospital doctor's team reports that the average cost of treatment of heart disease is 800 RO. To see if the average cost of treatment is different at a particular hospital, a researcher selected a random sample of 40 patients and found that the average cost of treatment is 400 RO. The standard deviation of the population is 350 RO. At test the claim of the hospital doctors.