A normal distribution has a mean of 80 and a standard deviation of 14. Compute the probability of a value between 75.0 and 90.0.

Question

a) .2022
b) .3595
c) .4017
d) None of the above

Answer 1

x1=75
x2=90

z1=(x1-mean)/standard dev. = -0.35
z2=(x2-mean)/standard dev. = 0.71

then look for the area table from your book, get for the equivalent value from z1 and z2, then get the difference of the two.. 0.7642-0.3632 = 0.401
thus, i assumed its C.