Question

if x is normally distributed with mean 12 and standard deviation 4 find p(x>=20)

Answer 1

Solution:

$\mu=12,\sigma=4 \\X\sim N(\mu,\sigma)$

$P(X\ge20)=1-P(X<20) \\=1-P(z<\dfrac{20-12}{4}) \\=1-P(z<2) \\=1-0.97725 \\=0.02275$