Answer
(a) $0.0351$ or $3.51\%$
(b) $0.0125$ or $1.25\%$
Work Step by Step
(a) For $N(531,121)$ and $x=750$, we can find:
$z=\frac{750-531}{121}\approx1.81$
use a z-table or a calculator, we can find the area to the right of this z-value to be about $1-0.9649=0.0351$ or $3.51\%$
(b) For $N(499,112)$ and $x=750$, we can find:
$z'=\frac{750-499}{112}\approx2.24$
use a z-table or a calculator, we can find the area to the right of this z-value to be about $1-0.9875=0.0125$ or $1.25\%$
The reason for the difference among the above results is because of the differences in the mean and SD values, which lead to differet z-values.
