1. X is a normal random variable with mean 50 and standard deviation 15. Compute k so that:

(a) P(X k) = 0.8413

(b) P(X k) = 0.3821

(c) P(30 X k) = 0.2238

2. X is a normal random variable:

(a) If the standard deviation is 10 and P(X 20) = 0.3085 find the value for .

(b) If = 3 and P(X 2) = 0.0778 find the variance of x.