91影视

Diastolic blood pressure measures for women are normally distributed with mean 70.2 mm Hg and standard deviation 11.2 mm Hg.

Let X be the random variable for the blood pressure of women.

Then,

\(\begin{aligned}{c}X \sim N\left( {\mu ,{\sigma ^2}} \right)\\ \sim N\left( {70.2,{{11.2}^2}} \right)\end{aligned}\)

The standardized score is the value \(x\) decreased by the mean and then divided by the standard deviation.

\(\begin{aligned}{c}z = \frac{{x - \mu }}{\sigma }\\ = \frac{{80 - 70.2}}{{11.2}}\\ = 0.875\\ \approx 0.88\end{aligned}\)

The probability to the left of 0.88 is the value in the cell interaction for the row with 0.8 and in the column with 0.8 in the standard normal probability tablewhich is 0.8106.

Thus,

\(\begin{aligned}{l}P(X < 80) = P(Z < 0.88)\\\;\;\;\;\;\;\;\;\;\;\;\;\;\;\; = 0.8106\end{aligned}\)

Thus, the probability that women haveblood pressure below 80 mm Hg is 0.8106.