Can someone explain how to figure this out

Brainlest answer can you find the area and circumference of a circle given the radius or diameter? if its yes or no explain why

Can someone explain to me how to do

In a certain city, the hourly wage of workers on temporary employment contracts is normally distributed. the mean is $15 and the standard deviation is $3. what percentage of temporary workers earn less than $12 per hour? a. 6% b. 16% c. 26% d. 36%