A sample of 50 gas stations throughout the US found the mean

A sample of 50 gas stations throughout the US found the mean price for a gallon of gas to be $3.61 with s = 0.16. Test the claim that the mean price for a gallon of gas is $3.90 per gallon. Find the critical value(s) and test statistic for this hypothesis test.

Solution

n = Sample size = 50

x bar = 3.61

s = 0.16

H0: x bar =3.90

Ha: xbar not equals 3.90

Two tailed test

Mean difference = -0.29

Std error =0.16/rt of 49 = 0.0223

t statistic = 12.6875

Let alpha be 0.05

critical values are t<-2 or t>+2