Tricky Systems of Equations (3) Problem

Expert replies

EMAN: Master | Next Rank: 500 Posts; Posts: 162; Joined: Sun Aug 09, 2009 4:17 pm; Location: Minnesota; Thanked: 1 times

by EMAN » Thu Nov 12, 2009 8:00 pm

Andrew will be half as old as Larry in 3 years. Andrew will also be one-third as old as Jerome in 5 years. If Jerome is 15 years older than Larry, how old is Andrew?

Please show work and strategy. I got a little confused manipulating the three equations and the explanation is the Manhattan guide is overly tedious in my opinion.

Like this post

Source: Beat The GMAT — Problem Solving | Thu Nov 12, 2009 8:00 pm

gmatv09: Master | Next Rank: 500 Posts; Posts: 256; Joined: Mon Aug 10, 2009 6:31 pm; Thanked: 3 times

by gmatv09 » Thu Nov 12, 2009 8:11 pm

A+3 = 1/2 (L+3) ==> 2A+6 = 3 + L

A+5 = 1/3 (J+5) ==> 3A+15 = 20 +L

================
A + 9 = 17
A = 8
J = 15+L

Like this post

EMAN: Master | Next Rank: 500 Posts; Posts: 162; Joined: Sun Aug 09, 2009 4:17 pm; Location: Minnesota; Thanked: 1 times

Great

by EMAN » Thu Nov 12, 2009 8:22 pm

That's good. It looks like I had a few minor errors in my equation setup. Where is 20 + L coming from?

Like this post

EMAN: Master | Next Rank: 500 Posts; Posts: 162; Joined: Sun Aug 09, 2009 4:17 pm; Location: Minnesota; Thanked: 1 times

by EMAN » Thu Nov 12, 2009 8:28 pm

I would think that 3A + 15 = J + 15 (as opposed to L + 20) which I understand would make the equation work.

Like this post

palvarez: Master | Next Rank: 500 Posts; Posts: 199; Joined: Sat Oct 24, 2009 4:43 pm; Thanked: 22 times; GMAT Score:710

Re: Tricky Systems of Equations (3) Problem

by palvarez » Thu Nov 12, 2009 11:53 pm

EMAN wrote:Andrew will be half as old as Larry in 3 years. Andrew will also be one-third as old as Jerome in 5 years. If Jerome is 15 years older than Larry, how old is Andrew?

Please show work and strategy. I got a little confused manipulating the three equations and the explanation is the Manhattan guide is overly tedious in my opinion.

Create a grid or matrix like table, with rows for L, A, J, and with colums for today, today +3, today + 5. Just put all variables. Then come up with equations: this way, you wont get lost in a maze of variables, etc.

Like this post

Post new topic Post Reply

• Page 1 of 1

GMAT Course Reviews

560 reviews

1168 reviews

431 reviews

359 reviews

147 reviews

5/5

5 Star (560 Reviews)

"Target Test Prep is the closest to the official version of the GMAT exam, about 99% accuracy in terms of the quality and quantity of information. The course has excellently created singular sets of focused lessons and tests for every possible topic that one could come across in the official GMAT exam."

"The TTP course maximizes the efficiency of the time you spend studying. It will take time and effort but I could almost guarantee that if you complete the course exactly as it is laid out you will get an amazing score. They also have a very responsive team willing to help with any questions you might have."

"TTP has two things that I think no other test prep company offers: A teaching approach that reinforces understanding and an attitude that will give you the mental preparedness needed to succeed on the test. TTP gives you a deep understanding of the concept you need to know while teaching you how to think."

Write a Review