Aresearcher wants to know if the average time in jail for robbery has increased from what it was several years ago when the average sentence was 7 years.
he obtains data on 400 more recent robberies and finds an average time served of 7.5 years.

if we assume the standard deviation is 3 years, what is the p-value of the test?

P-value of the test is 0.000434

Step-by-step explanation:

: average time in jail for robbery is same as it was several years ago

: average time in jail for robbery has increased from what it was several years ago

Test statistic can be calculated using

z= where

Then z= ≈3.33

Corresponding one tailed p-value of the test is 0.000434

34

step-by-step explanation: