Question

Find the value of the probability of the standard normal random variable Z corresponding to this area. (Round your answer to four decimal places.) P(−1.68 < Z < 1.23) =?

Answer 1

Solution:

We have to find: P(−1.68 < Z < 1.23) =.................?

P(−1.68 < Z < 1.23) = P( Z < 1.23 ) - P(Z < −1.68 )

Look in z table for z = 1.2 and 0.03 as well as for  z = -1.6 and 0.08  and find corresponding area.

P( Z < 1.23) =0.8907

and

P( Z< -1.68) = 0.0465

Thus

P(−1.68 < Z < 1.23) = P( Z < 1.23 ) - P(Z < −1.68 )

P(−1.68 < Z < 1.23) = 0.8907 - 0.0465

P(−1.68 < Z < 1.23) = 0.8442