An insurance company has determined that the cost of a certain medical procedure varies according to a normal distribution with a mean of $800 and a...

An insurance company has determined that the cost of a certain medical procedure varies according to a normal distribution with a mean of $800 and a standard deviation of $40. 

If a new insurance claim comes in for this particular medical procedure, what is the probability that the claim will be less than $900?

Question 28 options:

0.4938

0.0062

0.5987

0.9938

0.3085

Please teach me how to find the correct answer step by step please. Thanks you