In a school, 30 boys and 20 girls entered the Cayley competition. Certificates were awarded to $10 \%$ of the boys and $20 \%$ of the girls. Of the students who participated, the percentage that received certificates was
(A) 14
(B) 15
(C) 16
(D) 30
(E) 50
In a school, 30 boys and 20 girls entered the Cayley competition. Certificates were awarded to $10 \%$ of the boys and $20 \%$ of the girls. Of the students who participated, the percentage that received
certificates was
(A) 14
(B) 15
(C) 16
(D) 30
(E) 50

## Solution

If 30 boys entered the Cayley competition and $10 \%$ of them received certificates, this implies that (0.1)(30) or 3 boys received certificates. Of the 20 girls who entered the competition $(0.2)(20)$ or 4 girls received certificates. This implies that 7 students in total out of 50 received certificates.

Thus $14 \%$ of the students in total received certificates.

ANSWER: (A)