Five mathematics textbooks, T1, T2, T3, T4, and T5
2 shelves with only these 5 books
The number of pages in each book is a fraction of the total number of pages in the five books together
More than 1/2 of the total pages that comprise the five books are found on the lower shelf
We know that each book is a fraction of the total pages, so lets bring them in order
T1 = 11/60 = 11/60
T2 = 2/15 = 8/60
T3 = 7/30 = 14/60
T4 = 3/10 = 18/60
T5 = 3/20 = 9/60
So, we need to find out if T3 is on the lower shelf, given that more than 1/2 of the total page count is on the lower shelf
Given the statements,
(1) T2 and T4 have been placed on the lower shelf.
=> Lower shelf = T2 + T4 = 8/60 + 18/60 = 26/60
We know that lower shelf has more than half the page count
So lower shelf > 30/60
To satisfy this,
T1, T3 and T5 any of them can be in lower shelf to satisfy the condition i.e,
T1 + Lower shelf = 11/60 + 26/60 = 37/60 > 30/60
T3 + Lower shelf = 14/60 + 26/60 = 40/60 > 30/60
T5 + Lower shelf = 9/60 + 26/60 = 35/60 > 30/60
We cant know if T3 is on the lower shelf, Statement (1) is insufficient
(2) T1 and T5 have been placed on the upper shelf.
=> Upper shelf = T1 + T5 = 11/60 + 9/60 = 20/60
We know that lower shelf has more than half the pages (>30/60) and we have T2, T4 and T3 as the possibilities to be in the lower shelf
T2 = 8/60 , T3 = 14/60 , T4= 18/60
Only 2 combinations for the below shelf is possible to have more than half the pages (>30/60)
T2+T3+T4 = (8+14+18)/60 = 40/60 > 30/60
T3+T4 = (14+18)/60 = 32/60 > 30/60
In both these combinations T3 is in the lower shelf
=> Statement (2) is sufficient
(B) Statement (2) alone is sufficient, but Statement (1) is not