Question

1260 people visit a zoo in a day. The number of children is thrice the number of adults visiting the zoo. Out of all the visitors, one-fifth of the adults and one-fifth of the children are on a school trip. If out of the total visitors who are children on a school trip, the ratio of the males to females is 10:11, then find the number of female children visitors who are on a school trip.

• A. 99
• B. 90
• C. 89
• D. 111

Answer 1

The correct option is A 99

Let the number of adults visiting the zoo be x. Then, the number of children visiting the zoo will be 3x.

Total number of visitors = 1260

So,
x + 3x = 1260
⇒ 4x = 1260
⇒ x = 315

Thus,
Number of adults = 315
and, the number of children = 3 × 315 = 945

Number of visitors on the school trip:
$\text{Adults}=\frac{1}{5}\times 315=63$

$\text{Children}=\frac{1}{5}\times 945=189$


Now, the ratio of males to females = 10:11

So, number of male children on the $\text{school trip}=\frac{10}{21}\times 189=90$

And, the number of female children on the $\text{school trip}=\frac{11}{21}\times 189=99$

Thus, 99 of the total visitors were female children who were on a school trip to the zoo.