If the ratio of the number of teachers to the number of . .

This topic has expert replies
Moderator
Posts: 2058
Joined: Sun Oct 29, 2017 4:24 am
Thanked: 1 times
Followed by:5 members
If the ratio of the number of teachers to the number of students is the same in School District M and School District P, what is the ratio of the number of students in School District M to the number of students in School District P ?

(1) There are 10,000 more students in School District M than there are in School District P.
(2) The ratio of the number of teachers to the number of students in School District M is 1 to 20.

The OA is the option E.

Can any expert help me here? I am confused. I don't know how could I solve this DS question.

GMAT/MBA Expert

User avatar
Elite Legendary Member
Posts: 10392
Joined: Sun Jun 23, 2013 6:38 pm
Location: Palo Alto, CA
Thanked: 2867 times
Followed by:511 members
GMAT Score:800

by [email protected] » Thu Jan 04, 2018 10:53 am
Hi M7MBA,

We're told that the ratio of the number of teachers to the number of students is the SAME in School District M and School District P. We're asked for the ratio of the number of STUDENTS in School District M to the number of STUDENTS in School District P. This question can be solved by TESTing VALUES.

1) There are 10,000 more students in School District M than there are in School District P.

IF....
Students in M = 20,000
Students in P = 10,000
Then the ratio is 20,000:10,000 = 2:1

IF....
Students in M = 15,000
Students in P = 5,000
Then the ratio is 15,000:5,000 = 3:1
Fact 1 is INSUFFICIENT.

2) The ratio of the number of teachers to the number of students in School District M is 1 to 20.

Fact 2 tells us nothing about the number of teachers or students in District P.
Fact 2 is INSUFFICIENT.

Combined, we already have two TESTs that fit both Facts:
IF....
Teachers in M = 1,000
Students in M = 20,000
Students in P = 10,000
Then the ratio is 20,000:10,000 = 2:1

IF....
Teachers in M = 750
Students in M = 15,000
Students in P = 5,000
Then the ratio is 15,000:5,000 = 3:1
Combined, INSUFFICIENT

Final Answer: E

GMAT assassins aren't born, they're made,
Rich
Contact Rich at [email protected]
Image