#### Answer

a) $\dfrac{7}{13}$
b) $\dfrac{11}{13}$

#### Work Step by Step

We know that probability of an event is given by the formula $\frac{\text{number of favorable outcomes}}{\text{number of all outcomes}}.$
a) In total there are $4+9=13$ people, out of which $4$ are females (including ones under the age of $40$) and $3$ are under $40$ males.
Thus the probability of selecting a female or a male under $40$ is:
$=\dfrac{4+3}{13}=\dfrac{7}{13}$
b) In total there are $4+9=13$ people, out of which $9$ are males (including ones over the age of $40$) and $2$ are over $40$ females.
Thus the probability of selecting a male or over age $40$ is:
$=\dfrac{9+2}{13}=\dfrac{11}{13}$