A regional chain of fast-food restaurants would like to estimate the mean time requiredto serve its drive-thru customers.a. If the population standard deviation of service times is known to be 20 seconds, howlarge a sample must be used to estimate the mean service time for drive-thrucustomers if a margin of error of no more than ±6 seconds of the true mean with a90% level of confidence is required?b. Suppose the manager believes that a margin of error of ±6 seconds is too high andhas decided it should be cut by two thirds to a margin of error of ±2 seconds. Themanager believes that by cutting the margin of error by two thirds, the requiredsample size will triple. Is the manager correct?

Answered: Image /qna-images/answer/af4ad936-bf87-4345-a75e-cb1ba14547eb.jpg

Answered: A regional chain of fast-food…

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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An energy company wants to choose between two regions in a state to install energy-producing wind turbines. A researcher claims that the wind speed in Region A is less than the wind speed in Region B. To test the regions, the average wind speed is calculated for 90 days in each region. The mean wind speed in Region A is 13.7 miles per hour. Assume the population standard deviation is 2.8 miles per hour. The mean wind speed in Region B is 15.1 miles per hour. Assume the population standard deviation is 3.2 miles per hour. At a = 0.05, can the company support the researcher's claim? Complete parts (a) through (d) below. (a) Identify the claim and state H, and Ha What is the claim? O A. The wind speed in Region A is less than the wind speed in Region B. O B. The wind speed in Region A is not less than the wind speed in Region B. O C. The wind speed in Region A is not greater than the wind speed in Region B. O D. The wind speed in Region A is the same as the wind speed in Region B. Let…
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A recent survey of 1030 U.S. adults selected at random showed that 627 consider the occupation of firefighter to have very great prestige. Estimate the probability (to the nearest hundredth) that a U.S. adult selected at random thinks the occupation of firefighter has very great prestige.
It is calculated that, in order to estimate the true mean amount of money spent on textbooks this semester by U of M students to within $40 with 99% confidence, we need a sample of 100 students. What sample size would be required to estimate the true mean amount of money spent on textbooks to within $10 with 99% confidence?
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The president of a college wants to determine the mean number of units that college students take per semester. How large of a sample is required in order to be 99% sure that a sample mean will be off by no more than 1.25 units? An initial study suggested that the standard deviation is approximately 2.1 units.

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