HOw old is Larry today?

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

Redeem

This topic has expert replies

Post new topic Post Reply

Previous Topic Next Topic

ST: Master | Next Rank: 500 Posts; Posts: 191; Joined: Sat Feb 14, 2009 11:56 am; Thanked: 1 times

HOw old is Larry today?

by ST » Sun Apr 26, 2009 5:42 pm

If Sarah was 21 yeas old exactly 5 years ago, How old was Larry exactly 9 years ago?

1) Larry is now twice sarah's age

2) Twelve years ago, Jilly was 6 years older than Sarah and 20 years younger than Larry.

I go the 1) right but I am having little difficulty understanding 2) one.

St

Quote

Source: Beat The GMAT — Data Sufficiency | Sun Apr 26, 2009 5:42 pm

Vemuri: Legendary Member; Posts: 682; Joined: Fri Jan 16, 2009 2:40 am; Thanked: 32 times; Followed by:1 members

Re: HOw old is Larry today?

by Vemuri » Sun Apr 26, 2009 8:33 pm

My answer is D.

Question stem states that Sarah was 21 yrs 5 yrs back, i.e. (S-5) = 21 ==> S =26yrs now.

Stmt 1: Larry is twice as old as Sarah is now, L = 2S ==> L = 2*26. So, we can determine how old Larry was 9 years back. This statement is sufficient.

Stmt 2: The information given can be represented by the following equations:
(J-12) = (S-12) + 6
(J-12) = (L-12) - 20

==> (S-12)+6 = (L-12) -20
==> S - 6 = L -34
==> 26 - 6 = L -34 (we know from question that S is 26 yrs now)
==> L = 54yrs.

Hence both statements independently are sufficient to answer the question.

Quote

GMAT/MBA Expert

Ian Stewart: GMAT Instructor; Posts: 2623; Joined: Mon Jun 02, 2008 3:17 am; Location: Montreal; Thanked: 1090 times; Followed by:355 members; GMAT Score:780

Re: HOw old is Larry today?

by Ian Stewart » Mon Apr 27, 2009 5:27 am

ST wrote:If Sarah was 21 yeas old exactly 5 years ago, How old was Larry exactly 9 years ago?

2) Twelve years ago, Jilly was 6 years older than Sarah and 20 years younger than Larry.

St

Or you might notice, that Statement 2 simply tells us that Larry is 26 years older than Sarah (if Larry was 26 years older than Sarah twelve years ago, he's still 26 years older now). Since the question tells us that Sarah is 26 now, Larry is 52 now, so we can find his age nine years ago, and S2 is sufficient.

For online GMAT math tutoring, or to buy my higher-level Quant books and problem sets, contact me at ianstewartgmat at gmail.com

ianstewartgmat.com