math question?

Question

The mean monthly income of workers is $1500 with a standard deviation of $200. Given the distribution is normal, what percentage of workers earn more than $1300?

a. 97.72%

b. 30.85%

c. 93.32%

d. 84.13%

Answer 1

answer is d 84 percent.
one standard deviation in a normal distribution contains 68 percent of all workers. 1300-1700. with 1500 the mean. we need everything to the right of 1300. we take 68% and divide it by 2 to get the percentage located on each side of the mean. it will be 34 percent. so we know that 34 percent will earn between 1300-1500, and 50 percent will earn more then 1500. add them together, you get a 84 percent answer