1. Use standard normal distribution table and calculate:

a. P( Z < 3.8)

b. P( Z < 3.25)

c. P( Z > 2.58)

d. P( Z < -1.2)

2. Use standard normal distribution table and calculate:

a. P( 1.2 < Z < 2.4)

b. P( -0.52 < Z < 3.53)

c. P( -0.50 < Z < -0.30)

d. P( Z < 1.745)

3. Working life for a machine is normally distributed. Expected value for this machines working life is 200 hours and standard deviation is 10 hours. What is the probability, that this machine works over 220 hours P(X > 220)?

4. Working life for a product is normally distributed. Expected value for working life is 600 hours and standard deviation is 20 hours. What is the probability, that this product works:

a) over 660 hours

b) less than 550 hours