The Systolic Blood Pressures of the Patients at a Hospital

The systolic blood pressures of the patients at a hospital are normally distributed with a mean of 138 mm Hg and a standard deviation of 12.8 mm Hg. Find the two blood pressures having these properties: the mean is midway between them and 90% of all blood pressures are between them.

A) 117.9 mm Hg, 160.1 mm Hg
B) 121.6 mm Hg, 154.4 mm Hg
C) 126.5 mm Hg, 149.5 mm Hg
D) 116.9 mm Hg, 159.1 mm Hg