Q. In a class, 60% of students are from India and 50% of the students are girls. If 30% of the Indian students are girls, then what percentage of foreign students are boys?

Explanation : 

Percentage of Boys Among Foreign Students in a Class

The number of Indian students is 60% of 100 = 60.
The number of foreign students is 100 – 60 = 40.
The number of girls among Indian students is 30% of 60 = 18.
The total number of girls in the class is 50% of 100 = 50.
So, the number of girls among foreign students is 50 -18 =32
Therefore, the number of boys among foreign students is (40 -32) =8 So, the percentage of boys among foreign students is (8/40)*100=20% Hence, option (d) i.e. 20% is correct.