Victor, you did not show us the entire question. What is x? What is the population number? Is the distribution a normal distribution? No one can solve this question without knowing these.

Oops my bad,
The questions goes like this:
An aptitude test for deep sea divers produces a score which are normally distributed on a scale from 0 to 100. A randon sample of 160 divers were assessed, and each of their individual tests scores,x, was recorded. The results are summarised by (the rest in the photo)