Answer
(a) $\dfrac{25}{33}$
(b) $\dfrac{25}{33}$
Work Step by Step
Use the formula for a probability $P$ as: $\text{Probability}=\dfrac{\text{Number of favourable outcomes}}{\text{Number of all outcomes}}$
(a) Total students are: $18+15=33$ , out of which $18$ are freshmen (including females) and $15-8=7$ are sophomore females.
So, the probability is equal to $\dfrac{18+7}{33}=\dfrac{25}{33}$
(b) Total students are: $18+15=33$ , out of which $15$ are sophomores (including males) and $10$ are freshmen males.
So, the probability is equal to $\dfrac{15+10}{33}=\dfrac{25}{33}$
