An advertising executive wants to estimate the mean amount of time that consumers spend with digital media daily. From past studies, the standard deviation is estimated as 51 minutes. a. What sample size is needed if the executive wants to be 90% confident of being correct to within ±5 minutes? b. If 95% confidence is desired, how many consumers need to be selected?

An advertising executive wants to estimate the mean amount of time that consumers spend with digital media daily. From past studies, the standard deviation is estimated as 51 minutes. a. What sample size is needed if the executive wants to be 90% confident of being correct to within ±5 minutes? b. If 95% confidence is desired, how many consumers need to be selected?

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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The sample standard deviation is a measure of what?
The manager of a major retail store has taken a random sample of 25 customers. The average sale was $52.50. The population standard deviation is known to be $6.10. The manager would like to determine whether or not the mean sales by all customers are significantly more than $50. What is the p-value for the test?
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1. According to one study, the average hours of sleep on a weeknight for men was 6.9 hours with a standard deviation of 1.5 hours. a. Find the proportion of men who sleep for more than 8 hours per night. b. Find the proportion of men who sleep for less than 6 hours per night. c. Find the proportion of men who sleep between 6-8 hours per night. d. Find the number of hours that represents the 90th percentile.
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a.	What sample size is needed if the executive wants to be 90% confident of being correct to within ±5 minutes?
b.	If 95% confidence is desired, how many consumers need to be selected?