Verbal Reasoning - Arithmetic Reasoning - Discussion

Lets say total number of students = 180 --> Multiplication of all denominators(5,9,4) - Easy for calculation.

Number of girls = (3/5)(180) = 108.
Number of boys = 180-108 = 72.
Number of girls absent = (2/9)108 = 24.
Number of boys absent = (1/4)72 = 18.
Total number of students absent = Total girls absent + Total boys absent = 24+18 = 42.
Total number of students present = Total Students - Total students absent = 180-42 = 138.
Percent of students present = 138/180 = 23/30.

Not getting the solution. Anyone explain this clearly.

@Tim :

It is as simple as (1-2/5) i.e 3/5 of the boys are present because 2/5 are absent.

Explanation: Let a total number of students X.
Now the number of boys will be (1/3)X.
And the number of boys that are absent will be 2/5 * (1/3)X = (2/15)X.
So, the number of boys present in the class will be (1/3)X - (2/15)X = (3/15)X or (1/5)X.
Hence, the required fraction = (1/5)X / (1/3)X or 3/5.

In a class 1/3 are boys. If 2/5 of the boys are absent, what fraction of the boys are present?

Help me with these, please.

Thanks for explaining the answer. Useful question.