GATE CS 2021 Set 1 Q.1 (GA Q.1): Quantitative Aptitude

The ratio of boys to girls in a class is 7 to 3.

Among the options below, an acceptable value for the total number of students in the class is:

Official answer and solution

Official answer: C
From: Official GATE 2021 answer key

Solution

Express total students as a multiple of the sum of the ratio terms.

Let the number of boys be $7k$ and the number of girls be $3k$ , where $k$ is a positive integer. The total number of students in the class is $7k + 3k = 10k$ .

Because the number of students must be a positive integer, the total must be a multiple of 10. Among the given options (21, 37, 50, 73), only 50 is divisible by 10 (with $k = 5$ ).

Final answer

The answer is the one in the official GATE answer key. The solution is this site's own explanation.

Source

Paper: GATE 2021 Computer Science and Information Technology (CS, Set-1)
Question: 1 of 65, printed as GA Q.1
Section: General Aptitude

Report an error in this question

GATE questions are the work of the organising institutes. This site is independent and is not affiliated with them.

Question

Solution

Source