Question

The red blood cell counts​ (in millions of cells per​ microliter) for a population of adult males can be approximated by a normal​ distribution, with a mean of 5.2 million cells per microliter and a standard deviation of 0.5 million cells per microliter. What is the minimum red blood cell count that can be in the top ​24% of​ counts? What is the maximum red blood cell count that can be in the bottom 15​% of​ counts? can somebody help me?

Answer 1

5.55 million cells per microliter

4.68 million cells per microliter

Explanation:

First, use a chart or calculator to find the z-score for reach percentage.

P(Z > z) = 0.24

P(Z < z) = 1 − 0.24 = 0.76

z = 0.706

Next, use definition of z-score to find the value.

z = (x − μ) / σ

0.706 = (x − 5.2) / 0.5

x = 5.55

Repeat for the other percentage.

P(Z < z) = 0.15

z = -1.036

z = (x − μ) / σ

-1.036 = (x − 5.2) / 0.5

x = 4.68