Question

Given a normal distribution with a mean of 128 and a standard deviation of 15, what percentage of values is within the interval 83 to 173?
A. 32%
B. 50%
C. 68%
D. 95%
E. 99.7%

Answer 1

Answer:

E. 99.7%

Step-by-step explanation:

Calculate each z-score.

z = (x − μ) / σ

z = (173 − 128) / 15

z = 3

z = (x − μ) / σ

z = (83 − 128) / 15

z = -3

You can use a z-score table, or use the empirical rule.

P(-3 < z < 3) = 99.7%.