The question is:

"

*The recommended total blood cholesterol for a lower risk of heart disease is less than 200mg/dL. The total blood cholesterol for males aged 20 -29 is normally distributed with a mean of 195 and a standard deviation of 9.2. What is the probablity that a male aged 20 - 29 chosen at random has a total blood cholestoral greater than 200? What is the probability that a male aged 20 - 29 have a blood cholestoral in the range 180 - 200?*

My answer for the first part is 0.2981

If someone could just explain to me and point me in the right direction, that would be heaps of help. Thank you.