Question

provide an appropriate response. use the standard normal table to find the probability. assume that blood pressure readings are normally distributed with μ = 120 and σ = 8. a blood pressure reading of 145 or more may require medical attention. what percent of people have a blood pressure reading greater than 145?

a. 6.06%
b. 0.09%
c. 11.09%
d. 99.91%

Explanation:

Step1: Calculate the z - score

The formula for the z - score is $z=\frac{x-\mu}{\sigma}$, where $x = 145$, $\mu=120$ and $\sigma = 8$. So $z=\frac{145 - 120}{8}=\frac{25}{8}=3.125$.

Step2: Find the cumulative probability

Using the standard - normal table, we find the cumulative probability $P(Z\leq3.125)$. Looking up the value in the standard - normal table, we get a value close to $0.9991$.

Step3: Find the probability of $Z > 3.125$

We know that $P(Z>z)=1 - P(Z\leq z)$. So $P(Z > 3.125)=1 - 0.9991=0.0009 = 0.09\%$.

Answer:

B. 0.09%