The average operating life of a popular brand of tablets is know to be 2000 days, with a standard deviation of 150 days. Suppose you want to pick a random sample of 49 tablets from this brand. (a) What is the mean and standard error of the sampling distribution of the sample mean X¯ for a sample size of 49?  (b) What is the probability that such a sample mean will be within 50 days of the population mean?  (c) What is the probability that such a sample mean is less than 1975?  (d) What value of the sample mean will only be exceeded 6% of the time?

Calculus For The Life Sciences
2nd Edition
ISBN:9780321964038
Author:GREENWELL, Raymond N., RITCHEY, Nathan P., Lial, Margaret L.
Publisher:GREENWELL, Raymond N., RITCHEY, Nathan P., Lial, Margaret L.
Chapter13: Probability And Calculus
Section13.2: Expected Value And Variance Of Continuous Random Variables
Problem 10E
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The average operating life of a popular brand of tablets is know to be 2000 days, with a
standard deviation of 150 days. Suppose you want to pick a random sample of 49 tablets
from this brand.
(a) What is the mean and standard error of the sampling distribution of the sample
mean X¯ for a sample size of 49? 
(b) What is the probability that such a sample mean will be within 50 days of the
population mean? 
(c) What is the probability that such a sample mean is less than 1975? 
(d) What value of the sample mean will only be exceeded 6% of the time? 

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ISBN:
9780321964038
Author:
GREENWELL, Raymond N., RITCHEY, Nathan P., Lial, Margaret L.
Publisher:
Pearson Addison Wesley,