Question

What proportion of a normal distribution is located between z = -1.25 and z = +1.25?

a. 0.8944

b. 0.2112

c. 0.3944

d. 0.7888

Answer 1

Hi,

answer d: 0.7888

`Z(1.25)=0.8944\\Z(-1.25)=1-Z(1.25)\\\\Z(1.25)-Z(-1.25)=Z(1.25)-(1-Z(1.25))\\\\=2*Z(1.25)-1=2*0.8944-1\\\\\boxed{=0.7888}\\`