CAT 2020 Quant Question [Slot 2] with Solution 09

Let a, b, c represent number of students who opted for two subjects - Maths and Chemistry, Maths and Physics and Physics and Chemistry respectively.

Given, \(a + b = 23 - 18 = 5\)

and \(b + c = 25 - 18 = 7\)

Since a, b and c cannot be negative the least value for any of the three is 5 .

We get \(a + c + 18 = (23 + 25 - 18) - 2b\)

Minimum value of number of students who chose chemistry \( = 23 + 25 - 18 - 10 = 20\)