Question

A normal distribution has a mean of 142 and a standard deviation of 16. What is the probability that a randomly selected value lies between 142 and 174? A) 0.22 B) 0.34 C) 0.48 D) 0.54

Answer 1

$\mathbb P(142$

Approximately 95% of any normal distribution lies within two standard deviations of the mean, i.e. $\mathbb P(-2$. Because the distribution is symmetric, you have $\mathbb P(-2$, so $\mathbb P(0$.