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

Redeem

GMAT PREP

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Master | Next Rank: 500 Posts
Posts: 322
Joined: Fri Mar 27, 2009 3:56 pm
Thanked: 24 times
GMAT Score:710

GMAT PREP

by mike22629 » Sat Apr 18, 2009 3:59 pm
In a certain year, the difference between Mary and Jim's annual salaries was twice the difference between Mary and Kate's annual salaries. If Mary's annual salary was the highest of the three, what was the average salary of the three people that year?

1) Jim's Annual Salary was 30,000

2) Kate's Annual Salary was 40,000

Got the right answer but not sure if I approached it the best way. OA after a few responses.
Top
Source: — Data Sufficiency |
Senior | Next Rank: 100 Posts
Posts: 69
Joined: Wed Mar 04, 2009 4:15 pm
Thanked: 17 times
GMAT Score:780

by Feep » Sat Apr 18, 2009 9:36 pm
From the question, we can see that Mary > Jane > Jim in terms of salary, and that the difference between Mary and Jane is the same as the difference between Jane and Jim. (If Mary-Jim = 2(Mary-Jane), Mary - Jane = Jane - Jim)

(1) gives us the lowest annual salary at 30,000, but the upper values could be 40,000/50,000, or perhaps 100,000/170,000, which give wildly different averages. Insufficient.

(2) gives us the MIDDLE salary at 40,000, and we know that the difference in salary between Mary and Jane is the same as the difference between Jane and Jim. Therefore, those two values will be equidistant from 40,000, and thus will not affect the average of 40,000. Sufficient.

B.
I tutor GMAT/GRE level mathematics privately in the Los Angeles region, as well as via Skype for a discounted rate. Send me a message if you're interested.
Top
Master | Next Rank: 500 Posts
Posts: 322
Joined: Fri Mar 27, 2009 3:56 pm
Thanked: 24 times
GMAT Score:710

by mike22629 » Sun Apr 19, 2009 4:11 am
Ah I see. Thanks a lot freep. Yes the Correct answer is B.
Top
Legendary Member
Posts: 876
Joined: Thu Apr 10, 2008 8:14 am
Thanked: 13 times

by ketkoag » Mon Apr 20, 2009 10:56 am
In some cases, try to convert the word problem into equation and then reduce it to the basic equation so that u will get some hint about the condition the problem wants u to use. :)
Top
Legendary Member
Posts: 940
Joined: Tue Aug 26, 2008 3:22 am
Thanked: 55 times
Followed by:1 members

Re: GMAT PREP

by iamcste » Mon Apr 20, 2009 3:27 pm
mike22629 wrote:In a certain year, the difference between Mary and Jim's annual salaries was twice the difference between Mary and Kate's annual salaries. If Mary's annual salary was the highest of the three, what was the average salary of the three people that year?

1) Jim's Annual Salary was 30,000

2) Kate's Annual Salary was 40,000

Got the right answer but not sure if I approached it the best way. OA after a few responses.
Using simple algebra,

M-J=2(M-K) simplified to M=2k-J

Q: Average of M, K and J : (M+k+J)/3

Substitute for M, Q ( 2k-j+k+j)/3 =K So we need to know K

1. We dont know K..Insufficient

2. we know K..Sufficient. Choose B
Top
Master | Next Rank: 500 Posts
Posts: 377
Joined: Wed Sep 03, 2008 9:30 am
Thanked: 15 times
Followed by:2 members

by schumi_gmat » Tue Apr 21, 2009 11:32 am
This is an example of GMAT DS trap
Top
Post new topic Post Reply
• Page 1 of 1