A national grocer’s magazine reports the typical shopper spends 11.5 minutes in line waiting to check out. A sample of 19 shoppers at the local Farmer Jack’s showed a mean of 10.7 minutes with a standard deviation of 3.1 minutes. Is the waiting time at the local Farmer Jack’s less than that reported in the national magazine? Use the 0.050 significance level.

There is no significant evidence to support that waiting time is less than the mean reported.

Step-by-step explanation:

Given that :

Sample mean, x = 10.7

Standard deviation, s = 3.1

Sample, size , n = 19

H0: μ ≥ 11.5

H1: μ < 11.5

Using the t-test (sample size is small)

Test statistic :

(x - μ) / s/sqrt(n)

(10.7 - 11.5) / (3.1 / sqrt(19))

-0.8 / 0.7111887

= −1.124877

Tcritical = Tdf, 0.05

df = n - 1 ; T18,0.05/2 = - 2.101 (left tailed)

Decision region:

Reject H0 :

If Tstatistic < Tcritical

−1.124877 > - 2.101

Hence, We fail to reject H0

There is no significant evidence to support that waiting time is less than the mean reported.