jsasipriya wrote:

Of the 1,500 books purchased last year by a certain school district, how many are currently in use?

(1) 90% of the books used in the school district last year are currently in use.

(2) A total of 15,000 books were used in the school district last year.



I don't understand the explanation provided in the GMAT material. Can someone explain this please?

books purchased: 1,500 last year
now there may be two condition:
there may or may not be book in school before this 1500 book were purchased

statement 1) 90% of the books used in the school district last year are currently in use
this 90 % of 150. if we do this then we are assumin that there were no book in school district and one more thing this satement would have made sense if they would have said 90% of the books used in the school district were purchased last year
so staement 1 doesnt help us in any ways

(2) A total of 15,000 books were used in the school district last year.
now this says that 15000 book were used last year so now we know that before last year purchase there were 15000-1500=13500 books were there but does it say anything about books in use no so satement2 on its own is insufficient

now combining satement 1 and staement 2
info we have total books in school 15,000
90 % books of 15,000 are still in use but what it doesnt tell us that wether this 10 % books which are not in use .does it belong to bool purchased last year or book that were already there in school district.
so combining also doesnt help hence E