BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

common divisor

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Master | Next Rank: 500 Posts
Posts: 105
Joined: Sat May 17, 2008 8:12 pm
Thanked: 6 times

common divisor

by gmataug08 » Fri Nov 28, 2008 9:18 am
Two different numbers when divided by the same divisor left remainders of 11 and 21 respectively. When the numbers' sum was divided by the same divisor, the remainder was 4. What was the divisor?

a)36
b)28
c)12
d) 9
e) none

OA : b
Top
Source: — Problem Solving |
Master | Next Rank: 500 Posts
Posts: 110
Joined: Thu Oct 23, 2008 9:12 am
Location: India
Thanked: 9 times
Followed by:1 members

by austin » Fri Nov 28, 2008 9:33 am
When two different numbers (x,y) are divided by a number (d) and the remainders are r1 and r2, then when (x+y) is divided by d, the remainder is r1+r2.

If r1+r2 > d, resulting remainder r = r1 + r2 -d.

In this case, sum of remainders = 11+ 21 = 32.

When the numbers' sum was divided by the same divisor, the remainder was 4.

Since the remainder is 4, the number should be 32 - 4 = 28

eg. 5/12 - remainder 5; 8/12 - remainder 8; (5+8)/12 - remainder 13

r1+r2 > d (12). Therefore, resulting remainder = 13 -12 = 1
Top
Post new topic Post Reply
• Page 1 of 1