1- Scores on a certain exam are normally distributed with a mean of 90 and a variance of 25. What is the probability of obtaining a score less than 80?

2- If the area between the mean and Z= 1.26 in the z-distribution is 0.3962, the area to the left of the z= -1.26 is _______?

3- Suppose X is normally distributed with mean 50 and standard deviation 4, what is p(45 < x <58) ?

4- Suppose X is normally distributed with mean 50 and standard deviation 4. Find the probability of P( - 2.5 X +2.5).

5- Suppose X is normally distributed with mean 20 and standard deviation 4, find the value X such that p(X x) = 0.975