(c) Compute the rest value.\ The

z

test is a statistical test for the mean of a population. It can be used either when

n>=30

or when the population is normally distributed and

\\\\sigma

is known.\ The formula for the

z

test is\

z=((\\\\bar{x} )-\\\\mu )/((\\\\sigma )/(\\\\sqrt(n)))

\ where

\\\\bar{x} =

sample mean\

\\\\mu =

hypothesized population mean\

\\\\sigma =

population standard deviation\

n=

sample size\ Using the formula for the z-test,\

z=(145-120)/((39.2)/(\\\\sqrt(48)))\ =4.42

\ Hence, the test value, rounded to 2 decimal places, is

z=4.42

.\ Step 4\ (d) Make the decision.

The z test is a statistical test for the mean of a population. It can be used either when n30 or when the population is normally distributed and is known. The formula for the z test is z=X where X= sample mean = hypothesized population mean = population standard deviation n= sample size Using the formula for the z-test, z=39.2/48145120=4.42 Hence, the test value, rounded to 2 decimal places, is z=4.42. Step 4 (d) Make the decision