Question

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of a death-row inmate has changeed since then. She randomly selects 32 death-row inmates and finds that their mean age is 39.4, with a standard devialion of 8.4. Construuct a 95% confidence interval about the mean age. What does the interval imply? Click the icon to view the table critical t-values Choose the correct hypoltheses. H H (Type intagers or decimals. Do not round.) Construct a 95 % confidence interval about the mean age. The lower bound is (Round to two decimal places as needed.) What does the interval imply? QA Since the mean age from the earlier year is ot contained in the interval, there is sufficient evidence to conclude that the mean age had changed. O B. Since the mean age from the earlier year is not contained in the interval, there is not sufficient evidence to conclude that the mean age had changed O C. Since the mean age from the earlier year is contained in the interval, there is sufficient evidence to conclude that the mean age had changed. O D. Since the mean age from the earlier year is contained in the interval, there is not sufficient evidence to conclude that the mean age had changed.

Answer 1

a) The null and alternative hypothesis are:

Ho: 40.3

H 40.3

Test the hypothesis at level of significance

0.05

b) Given

n32, 39.4, s 8.4!

The degrees of freedom are df = n-1 = 32-1 = 31

The critical value at
0.05
with 31 df is,
to.05/2,31 2.04

The 95% confidence interval about the mean age is:

CI ta/2,31(-

8.4 39.4 t to.05/2,3132 = 39.4土2.04(1.484) 39.4 土3.029 - (36.371,42.429) (36.37,42.43)

The lower bound = 36.37

The upper bound = 42.43

c) Since the mean age from the earlier year is contained in the inteval,there is not sufficient evidence to conclude that the mean age has changed

Answer: option D