Question

in order to fairly set flat rates for auto mechanics, a shop foreman needs to estimate the average time it takes to replace a fuel pump in a car. how large a sample must he select if he wants to be 99% confident that the true average time is within 15 minutes of the sample average? assume the standard deviation of all times is 30 minutes.

Answer 1

The value of n is 25  according to standard deviation in the question.

What is standard deviation?

Standard Deviation is a measure that shows what quantity variation (such as unfold, dispersion, spread,) from the mean exists. the quality deviation indicates a “typical” deviation from the mean. it's a well-liked live of variability as a result of it returns to the first units of live of the info set.

Main body:

s = 30 minutes

C.I. = 99%

mean = 15 minutes

z value for 99% = 2.58

mean = z*s/√n

15  = 2.58 * 30 / √n

√n = 5.06

n = 25

Hence the value of n is 25 .

To know more about standard deviation click on the link below

brainly.com/question/475676

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