Find the two standard scores z that correspond to the follow

Find the two standard scores (z) that correspond to the following. (Enter your answers from smallest to largest. Give your answers correct to two decimal places.)

(a) The middle 79% of a normal distribution is bounded by them.
and  
(b) The middle 87% of a normal distribution is bounded by them.
and

Solution

a)

if the middle 79% of a normal distribution is bounded by them

and our table only gives us the tailed of normal distribution

1 - 0.79 = 0.21 / 2 = 0.105

Z= +/- 1.25

b)

1 - 0.87 = 0.13/ 2 = 0.065

Z= +/- 1.51