Land's Bend sells a wide variety of outdoor equipment and clothing. The company sells both through mail order and via the internet. Random samples of sales receiptswere studied for mail order sales and internet sales, with the total purchase being recorded for each sale. A random sample of 12 sales receipts for mail order salesresults in a mean sale amount of $94.50 with a standard deviation of $19.25. A random sample of 17 sales receipts for internet sales results in a mean sale amount of$81.80 with a standard deviation of $20.75. Using this data, find the 80 % confidence interval for the true mean difference between the mean amount of mail orderpurchases 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.

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ENGR.ECONOMIC ANALYSIS

14th Edition

ISBN:9780190931919

Author:NEWNAN

Publisher:NEWNAN

Chapter1: Making Economics Decisions

Section: Chapter Questions

Problem 1QTC

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Question: Godrej soap manufacturing company was distributing a particular brand of soap through a large number of retail shops. Before a heavy advertisement campaign, the mean sales per week per shop was 140 dozens. After the campaign, a sample of 26 shops was taken and the mean sales was found to be 147 dozens with standard deviation 16. Can you consider the advertisement effective?
7. It is well known that car buyers often add accessories to their new cars. A sample of 179 Ottawa purchasers yielded a sample mean of $5000 worth of accessories added to the purchase above the base sticker price. Suppose the cost of accessories purchased for all Ottawa has a standard deviation of $1500. (a) Calculate a 95% confidence interval for the average cost of accessories on Ottawa. - Section Break - (b) Determine the margin of error in estimating the average cost of accessories on Ottawa. (c) What sample size would be required to reduce the margin of error by 50%?
A survey conducted by the American automobile association show that a family of four spent an average of $215.60 per day while on vacation. It's supposed to sample of 64 families of four vacationing at Niagara Falls resulted in a sample mean of $256.45 per day and a sample standard deviation of $76.50
10. 7 students were asked how many pencils they had. The responses were 2, 5, 8, 3, 1, 6, and 4. a. Calculate the sample mean 8. Find the sample standard deviation C Find the Q1, Q3, and the interquartile range.
2) You work for the FTC. A manufacturer of detergent claims that the mean weight of detergent is at least 6.5 lb. You take a random sample of 64 containers. You calculate the sample average to be 6.43 lb. with a standard deviation of .14 lb. At the 0.02 level of significance, is the manufacturer correct?
Eddie Clauer 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 7 sales receipts for mail order sales results in a mean sale amount of $81.10 with a standard deviation of $23.25. A random sample of 15 sales receipts for internet sales results in a mean sale amount of $64.30 with a standard deviation of $28.25. Using this data, find the 90 % 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 1 of 3: Find the critical value that should be used in constructing the confidence interval. Round your answer to three decimal places.
A group of local businessmen is thinking about developing land into a shopping mall. To evaluate the desirability of the location, they count the number of shoppers who visit the neighboring shopping center each day. A random sample of 54 days reveals a daily average of 126 shoppers with a standard deviation of 48 shoppers. The businessmen will develop the land if the average number of shoppers per day is more than 110. Based on the sample data, should the businessmen develop the land? Perform a hypothesis test and use a significance level of a = 0.10. Assume the population of the number of daily shoppers is approximately normally distributed. Step 2 of 3: Compute the value of the test statistic. Round your answer to three decimal places.
In 2017, Americans spent a record-high $9.1 billion on Halloween- related purchases (the balance website). Sample data showing the amount, in dollars, that 16 adults spent on a Halloween costume are as follows. 13 69 23 65 32 36 31 43 52 17 13 95 46 32 66 24 a. What is the estimate of the population mean amount adults spend on a Halloween costume (to 2 decimals)? $ 41.06 b. What is the sample standard deviation (to 2 decimals)? $ c. Provide a 95% confidence interval estimate of the population standard deviation for the amount adults spend on a Halloween costume (to 2 decimals). Use Table 3 of Appendix B. $ 17.14 ≤0≤ $
2. The average hour spent in computer by 20 senior high school students during online class is 7 hours with a standard deviation of 2 hours. Construct a 98% confidence interval of the average hour spent by all senior high school students. Identify the width of the interval. 20
A manufacturer fills soda bottles. Periodically the company tests to see if there is a difference between the mean amounts of soda put in bottles of regular cola and diet cola. A random sample of 13 bottles of regular cola has a mean of 497.9 mL of soda with a standard deviation of 3.4 mL. A random sample of 11 bottles of diet cola has a mean of 502.6 mL of soda with a standard deviation of 4.3 mL. Test the claim that there is a difference between the mean fill levels for the two types of soda using a 0.05 level of significance. Assume that both populations are approximately normal and that the population variances are not equal since different machines are used to fill bottles of regular cola and diet cola. Let bottles of regular cola be Population 1 and let bottles of diet cola be Population 2. Step 2 of 3: Compute the value of the test statistic. Round your answer to three decimal places. Answer 2 Points Кeypad Keyboard Shortcut
A manufacturer claims that the calling range (in feet) of its 900-MHz cordless telephone is greater than that of its leading competitor. A sample of 1010 phones from the manufacturer had a mean range of 11801180 feet with a standard deviation of 4141 feet. A sample of 2020 similar phones from its competitor had a mean range of 11101110 feet with a standard deviation of 3535 feet. Do the results support the manufacturer's claim? Let μ1�1 be the true mean range of the manufacturer's cordless telephone and μ2�2 be the true mean range of the competitor's cordless telephone. Use a significance level of α=0.01�=0.01 for the test. Assume that the population variances are equal and that the two populations are normally distributed. Step 2 of 4 : Compute the value of the t test statistic. Round your answer to three decimal places.

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