Question

directions
answer the questions below to check your understanding and move forward in the course! this quiz is not graded.
if an exam has a mean of 185 and a standard deviation of 13, what is the probability a person would score less than 170?
select the correct answer
0.6251
0.1251
0.8749
0.3749

Explanation:

Step1: Calculate the z - score

The formula for the z - score is $z=\frac{x-\mu}{\sigma}$, where $x = 170$, $\mu=185$, and $\sigma = 13$. So $z=\frac{170 - 185}{13}=\frac{- 15}{13}\approx - 1.15$.

Step2: Find the probability from the standard normal table

We want to find $P(X<170)$, which is equivalent to $P(Z < - 1.15)$ in the standard - normal distribution. Looking up the value of $P(Z < - 1.15)$ in the standard - normal table, we get $0.1251$.

Answer:

0.1251