Question

In 2002, the mean age of an inmate on death row was 40.7 years, according to data obtained from
the U.S. Department of Justice. A sociologist wants to test the claim that the mean age of a death row inmate
has changed since then. She randomly selects 32 death-row inmates and finds that their mean age is 37.9, with a
standard deviation of 9.6. Test the sociologist’s claim using a 1% level of significance.

Answer 1

Here claim is that mean has changed from 40.7

So hypothesis here is vs

As population standard deviation is not known so we will use t distribution

Test statistics is

So P value is TDIST(1.65,31,2)=0.1090> alpha=0.01

Hence we fail to reject the null hypothesis

So we do not have sufficient evidence to support the claim that mean is different from 40.7