Local Health Authorities Are Concerned That the Hectic Pace in Their

Essay

Local health authorities are concerned that the hectic pace in their city has elevated
the stress, and thus the blood pressure, of women. The authorities will study this
issue by measuring the blood pressure of a random sample of women in the city and
estimating the mean blood pressure, μ , of women in the city. Blood pressure is
approximately normally distributed in humans, and a previous study suggests the
population standard deviation of women's blood pressure is about 8 mm Hg.
Suppose the health authorities accept this value as a reasonable estimate of the
standard deviation of blood pressure of today's women in this city. If it is desired to
estimate μ to within 1.0 mm Hg with 95% confidence, what is the minimum sample
size that is necessary?