Answer
The margin of error for population A will be smaller.
Work Step by Step
$E=t_{\frac{α}{2}}.\frac{s}{\sqrt n}$ (margin of error)
Both samples have the same size: $n=75$
The level of confidence is the same. It implies the same $t_{\frac{α}{2}}$
But, since population A is made up of college students, their age has a lower standard deviation.
