Age problems

Find out how Beat The GMAT members tackled GMAT test prep with positive results. Get tips on GMAT test prep materials, online courses, study tips, and more.
This topic has expert replies
User avatar
Junior | Next Rank: 30 Posts
Posts: 14
Joined: Sun May 27, 2012 2:00 am

Age problems

by R.K » Wed May 30, 2012 10:06 am
A fathers age is 30 times older than his son however after 18 years he will only be thrice as old as son find the present age of father?
Source: — I just Beat The GMAT! |

User avatar
MBA Admissions Consultant
Posts: 2279
Joined: Fri Nov 11, 2011 7:51 am
Location: New York
Thanked: 660 times
Followed by:266 members
GMAT Score:770

by Jim@StratusPrep » Wed May 30, 2012 10:23 am
Equation 1 --> F = 30S
Equation 2 (remember to add 18 to both) --> F + 18 = 3(S +18)

Normally, I would set up the problem and solve for F, but this example it is a bit easier the other way despite the extra step.

Substituting:

30S + 18 = 3S + 54
-3S - 18 -3S - 18

27S = 36
S = 1 1/3

F = 30 (1 1/3) = 40
GMAT Answers provides a world class adaptive learning platform.
-- Push button course navigation to simplify planning
-- Daily assignments to fit your exam timeline
-- Organized review that is tailored based on your abiility
-- 1,000s of unique GMAT questions
-- 100s of handwritten 'digital flip books' for OG questions
-- 100% Free Trial and less than $20 per month after.
-- Free GMAT Quantitative Review

Image