# Verbal Reasoning - Arithmetic Reasoning - Discussion

### Discussion :: Arithmetic Reasoning - Section 1 (Q.No.21)

21.

In a class, there are 18 boys who are over 160 cm tall. If these constitute three-fourths of the boys and the total number of boys is two-thirds of the total number of students in the class, what is the number of girls in the class ?

 [A]. 6 [B]. 12 [C]. 18 [D]. 24

Explanation:

Let the number of boys be x. Then, (3/4)x = 18 or x = 18 x(4/3) = 24.

If total number of students is y, then (2/3) y = 24 or y = 24 x (3/2) = 36.

Therefore Number of girls in the class = (36 - 24) = 12.

 Ayush Choudhary said: (Aug 23, 2014) I have not understand how to do this help me?

 Imran Ali said: (Sep 17, 2014) Number of boys in the class say x. 18 are above 160cm and are constitute as 3/4 of the boys, hence 3/4*x = 18 ===> 24. Total number of student in the class say y. Total number of boys is 2/3 of the total number of student. 2/3y = 24 ===> y= 36. Number of girls in the class, Girls in the class = total student - total boys. Girls in the class = 36 - 24. Girls in the class = 12. Hence answer B is right.

 Mohit said: (Jan 15, 2017) It's so easy guys. Let the num of student in class = x. Then num of boys = 2x/3, And num of girls = x - 2x/3 = x/3, Now given that (2x/3)(3/4) = 18, Hence x = 36. So, the num of girls = x/3 = 36/3 = 12.

 Lakshminarasimha said: (Jul 23, 2018) 3/4part is boy i.e 18 boys are 160cm. 3*6 = 18, 4*6 = 24. 2/3 part 2 part boys=24, Girl 1 part =12.