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Register now and save up to $200 Available with Beat the GMAT members only code • 1 Hour Free BEAT THE GMAT EXCLUSIVE Available with Beat the GMAT members only code • Free Practice Test & Review How would you score if you took the GMAT Available with Beat the GMAT members only code • 5 Day FREE Trial Study Smarter, Not Harder Available with Beat the GMAT members only code • Get 300+ Practice Questions 25 Video lessons and 6 Webinars for FREE Available with Beat the GMAT members only code • 5-Day Free Trial 5-day free, full-access trial TTP Quant Available with Beat the GMAT members only code • Reach higher with Artificial Intelligence. Guaranteed Now free for 30 days Available with Beat the GMAT members only code • Free Veritas GMAT Class Experience Lesson 1 Live Free Available with Beat the GMAT members only code ## A math prob, pls help This topic has 1 expert reply and 2 member replies tracyyahoo Master | Next Rank: 500 Posts Joined 14 Jun 2011 Posted: 147 messages Upvotes: 3 #### A math prob, pls help Mon Oct 03, 2011 10:15 pm Alex deposited x dollars into a new account that earned 8 percent annual interest, compounded annually. One year later Alex deposited an additional x dollars into the account. If there were no other transactions and if the account contained w dollars at the end of two years, which of the following expresses x in terms of w ? a: w/1+1.08 b: w/1.08+1.16 c: w/1.16+1.24 d: w/1.08+1.08^2 e: w/1.08^2+1.08^2 my approach is : deposit is x: (1.08){x(1+0.08)}=w, then x=w/1.16*1.08 Am I missing anything here?? Pls explain.... No, No, I calculate in a wrong way, I chose B~~!!!! Pls explain in details and give me a full calculation process!!! Thank you Last edited by tracyyahoo on Mon Oct 03, 2011 10:34 pm; edited 2 times in total ### GMAT/MBA Expert Rich.C@EMPOWERgmat.com Elite Legendary Member Joined 23 Jun 2013 Posted: 9316 messages Followed by: 478 members Upvotes: 2867 GMAT Score: 800 Tue Mar 20, 2018 2:07 pm Hi All, We're told that Alex deposited X dollars into a new account that earned 8 percent annual interest, compounded annually and 1 year later Alex deposited an additional X dollars into the account. We're asked - if there were no other transactions and if the account contained W dollars at the end of 2 years, which of the following expresses X in terms of W. This question can be solved by TESTing VALUES. Let's start with X =$100
After 1 year, this $100 would earn 8% interest -->$100 + $8 =$108 after 1 year
Then Alex deposits another $100 -->$108 + $100 =$208
After 1 year, this $208 would earn 8% interest -->$208 + $16.64 =$224.64 after 2 years
Thus, we're looking for an answer that equals 100 when W=224.64 is inserted.

While the answers might 'look complex', we're ultimately looking for one that has a denominator equal to 2.2464 (since that's what we'd have to divide our W by to get to 100). You can eliminate 3 answers immediately (Answers A, B and C won't give you that exact denominator). By calculating either of the remaining two answers, you'll know that you either have the correct answer OR you don't - and the other answer will be the correct answer...

GMAT assassins aren't born, they're made,
Rich

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Contact Rich at Rich.C@empowergmat.com

shankar.ashwin Legendary Member
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Mon Oct 03, 2011 10:27 pm
At the end of 2 years you have

w = 1.08(1.08x) + 1.08x

1.08(1.08x) - 8% interest on amount after first year
1.08x - Interest on 'x' deposited the second year.

so,

x = w/1.08+1.08^2 D

It shoud be (1+1.08) and not (1 + 0.08)

sl750 Master | Next Rank: 500 Posts
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Mon Oct 03, 2011 10:24 pm

Answer d can be written as w/1.08(1+1.08) = w/1.08*2.08

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