Claim: The mean systolic blood pressure of all healthy adults is less than than

121

mm Hg. Sample data: For

297

healthy adults, the mean systolic blood pressure level is

120.55

mm Hg and the standard deviation is

15.08

mm Hg. The null and alternative hypotheses are

H0:

=121

and

H1:

<121.

Find the value of the test statistic.