Question

If the systolic blood pressure for a certain group of obese people has a mean of 132 and a standard deviation of 8, find the probability that a randomly selected person will have below 148 blood pressure. Assume the variable is normally distributed.

Answer 1

We have a normal distribution, $\mu=132, \sigma=8.$

Let's convert it to the standard normal distribution,

$z=\cfrac{x-\mu}{\sigma}=\cfrac{148-132}{8}=2;\\ P(X<148)=P(Z<2)=0.9772.$