Problem Solving

can someone explain this rate question again?

I just can't seem to arrive at the answer.

https://www.beatthegmat.com/ps-questions ... t7201.html


Thanks

Your image is not coming properly. Can u pls "add image" it again?

oh, it came up when i clicked it, but here it is again.

thanks

max books that can be borrowed by 30 students is 30 * 2 =60

Now 2 students dont borrow any book,
remaining student = 28
remaining books = 60

12 students each borrow 1 book,
remaining student = 16
remaining books = 48

10 students each borrow 2 book,
remaining student = 6
remaining books = 28

now 28 books to be borrowed among 6 students.
These students can't borrow 1 or 2 books.... This is the key...

So lets Assume 15 books by a student
remaining student = 5
remaining books = 13

not possible, as someone have to borrow 2 books then...

So next highest 13 books borrowed by a student
again...
remaining student = 5
remaining books = 15

this will do, So 13 books

Ans D