Independent solution

How to solve this Conditional Probability question

Setup

Setup

Split the portfolio by sex and by whether age exceeds the cutoff.

NM=0.54(900)=486,NF=414N_M=0.54(900)=486,\qquad N_F=414
N25=900395=505N_{\le25}=900-395=505

Model

Model

Within the female group, the probability of being at or below the cutoff is the complement of the supplied older-age probability.

NF,25=414(10.43)=235.98N_{F,\le25}=414(1-0.43)=235.98

Compute

Compute

Subtract the female portion from the full under-25 group and condition on that group.

NM,25=505235.98=269.02N_{M,\le25}=505-235.98=269.02
Pr(M25)=269.02505=0.5327129\Pr(M\mid \le25)=\frac{269.02}{505}=0.5327129

Answer

Answer

The conditional male proportion rounds to 0.53.

0.53(B)\boxed{0.53\quad\text{(B)}}