Shelves

[andret]

DS:

Currently there are 50 picture books on each shelf in the children's section of a library. If these books were to be placed on smaller shelves with 30 picture books on each shelf, how many of the smaller shelves would be needed to hold all of these books?

(1) The number of smaller shelves needed is 6 more than the current number of shelves.
(2) Currently there are 9 shelves in the children's section.

[mk101]

The answer should be "D"

(1) The number of smaller shelves needed is 6 more than the current number of shelves.
.
Suff - Let the initial no = n therefore Total books =50n = 30 (n+6)
should give us the answer

(2) Currently there are 9 shelves in the children’s section

.

if there are 9 shelves then the number of books = 50 x 9 =450

No of smaller shelves reqd = 450/30 =15

sufficient

[rishab1988]

Let the total no of books =t

Then the no of shelves in children's section = t/50

The no of shelves [smaller ones] =t/30

So basically the question is asking " What are the total no of books?"

1)

t/30 -t/50 =6 [ No of smaller shelves [t/30] are 6 + No of shelves in children's section [t/50]].You know children's because of the hypothetical were and the conditional would [ they weren't actually placed on them]

t[2/150]=6
t=450

We know total no of books .therefore we can find no of shelves.

2) Currently there are 9 shelves.

This too is sufficient because the question says " 50 picture books on each shelf in the children's section of a library",that is,no shelf is empty.

So total no of books = 50*9=450.

Since we know total,we can find the no of smaller shelves.

Hence sufficient

Answer should be D

[Remember: If there weren't the words 'on each shelf" ,B would have been insufficient,because we don't know on how many shelves,actually,there are books.]

[andret]

Thanks. That helped!