Question

The figure shows a normal distribution curve with a mean of 3.47 and a standard deviation of 0.81. find the value of x, given that 80% of the values are greater than x

a)2.06

b)2.79

c)5.13

d)1.95

Answer 1

b) 2.79

Explanation:

Use a calculator or table to find the z-score that corresponds to P(x<z) = 0.20.

z ≈ -0.84

z = (x − μ) / σ

-0.84 = (x − 3.47) / 0.81

x = 2.79