GATEWAY TO GRADUATE STUDY
Home | Contact Us | Site Map
Question 1

There are 5 doors to a lecture room. What is the number of ways that a student enters the room and leaves it by different doors?
  1. 10
  2. 9
  3. 20
  4. 625
  5. 1024
The correct Answer is 20 ways and the correct Choice is (C).

Explanatory Answer

There are 5 doors to the lecture room.
The student would have entered the lecture room using one of the 5 doors in 5 ways.

Now, if she has to leave the lecture room by a different door, then she has to take one of the remaining 4 doors.
She can select one of the four doors to exit the lecture room in 4 ways.

Therefore, the total number of ways a student enters the lecture room and leaves it by different doors = 5 * 4 = 20 ways.
GRE Prep Classes India
TOPGRE's next batch is a 10-weekend, 60 hour program. Classes at our Anna Nagar Center from Aug 7, 10. Expert Faculty. Small batch size.
GRE Coaching classes
GRE Prep Classes India
Here is what our students have to say about our classroom program for GRE. Our students have made it to some of the top graduate schools in the US.
GRE Coaching classes
GRE Mailing List, forums
Get on top of your GRE preparation. Get free practice questions periodically sent by mail. Plus have your queries answered by peers and experts.
GRE Coaching classes


follow TOPGRE on Facebook
follow TOPGRE on Twitter
GRE, ETS and other trademarks are the property of the respective trademark holders. None of the trademark holders are affiliated with Test Catalyst or this web site.