Question

Find the following:

a) Z.99  

b) Z.02

c) Z.90

d) Z.01

Answer 1

Solution :

Using standard normal table,

a) Z_0.99

P(Z > z) = 0.99

1 - P(Z < z) = 0.99

P(Z <z) = 1 - 0.99 = 0.01

P(Z < -2.33) = 0.01

Z_0.99 = -2.33

(b) Z_0.02

P(Z > z) = 0.02

1 - P(Z < z) = 0.02

P(Z < z) = 1 - 0.02 = 0.98

P(Z < 2.05) = 0.98

Z_0.02 = 2.05

c)

P(Z > z) = 0.90

1 - P(Z < z) = 0.90

P(Z <z) = 1 - 0.90 = 0.10

P(Z < -1.28) = 0.10

Z_0.90 = -1.28

d)

P(Z > z) = 0.01

1 - P(Z < z) = 0.01

P(Z <z) = 1 - 0.01 = 0.99

P(Z < 2.33) = 0.99

Z_0.01 = 2.33