Let the random variable Z follow a standard normal distribut

Let the random variable Z follow a standard normal distribution.

                  a. The probability is 0.70 that Z is less than what number?

                  b. The probability is 0.25 that Z is less than what number?

                  c. The probability is 0.2 that Z is greater than what number?

                  d. The probability is 0.6 that Z is greater than what number?

Solution

a.

P(z < b) = 0.70

b=0.525

b

P(z < b) = 0.25

b= -0.675

c.

P(z > b) = 0.20

P(z < b) = 0.80

b= 0.84

d.

P(z > b) = 0.60

P(z < b) = 0.4

b= 0.27