AAPL wrote:A certain section of a library currently has how many books?

(1) If 20 additional books are bought for this section and 10 of the present books are moved into a different section, then there are 100 books left in this section.
(2) If no additional books are bought for this section but 30 of the present books are moved into a different section, there will be fewer than 50 books in this section

The OA is A.

Is there a strategic approach to this question? Can anyone help? Thanks!

We have to find out the number of books a certain section of a library currently has.

Let's take each statement one by one.

(1) If 20 additional books are bought for this section and 10 of the present books are moved into a different section, then there are 100 books left in this section.

Say there are x number of books in the section.

Thus, x + 20 - 10 = 100

=> x = 90. The section has 90 books. Sufficient.

(2) If no additional books are bought for this section but 30 of the present books are moved into a different section, there will be fewer than 50 books in this section.

Say there are x number of books in the section.

Thus, x - 30 < 50

x < 80. No unique value possible. Insufficient.

What is the source of the question? Though the answer to the question is A, the question is not a genuine GMAT type. The information from Statement 1 (Says, the number of books = 90) and the information from Statement 2 (Says, the number of books is less than 80) are inconsistent. If Statement 1 is correct, then from Statement 2, we must render x > 80.

The correct answer: A

Hope this helps!

-Jay
_________________
Manhattan Review GMAT Prep

Locations: Manhattan Review India | Mehdipatnam GMAT Coaching | Madhapur GMAT Courses | Manhattan Review Hyderabad | and many more...

Schedule your free consultation with an experienced GMAT Prep Advisor! Click here.