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Problem Solving#2: Exponents

This topic has 4 member replies
Mark Dabral Guest

Problem Solving#2: Exponents

Mon Feb 12, 2007 11:54 pm
Source: Inspired by recent questions on the GMAT test

Hi,

I am noticing a lot of very difficult questions that are being posted on the forum and I want to emphasize that many questions on the GMAT or not as hard and rely on one or two simple twists. The problems on the surface may seem easy, but can be quite challenging.

In this problem, I would like to illustrate how some basic ideas in exponents are being tested in the exam recently.

It is a bit time consuming for me to write these questions because I have to change the actual GMAT question (copyright rules etc.) and spend time on generating all the possible traps.

Cheers,
Mark
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Last edited by Mark Dabral on Wed Feb 14, 2007 11:00 am; edited 2 times in total

Neo2000 Legendary Member
Joined
27 Jan 2007
Posted:
519 messages
31
Test Date:
30/09
Target GMAT Score:
710
Tue Feb 13, 2007 7:52 am
I got D.

Not sure if I should post my explanation.

Mark, further clarification would be great. Should I post my explanation right away or wait a specific amount of time before editing my post ?

Edit:Explaining my method

I simply converted everything to decimals and simplified.
I got 3.125 in the numerator and .625 in the denominator.

Last edited by Neo2000 on Wed Feb 14, 2007 4:07 am; edited 1 time in total

Mark Dabral Guest
Tue Feb 13, 2007 11:24 am
I would like to see if others would post their answers as well. Go ahead and post your explanation tomorrow. Afterwards, I would like to highlight some of the common mistakes students make.

Thanks,
Mark

Mark Dabral Guest
Tue Feb 13, 2007 10:16 pm
Neo, your answer is correct. This is a problem that troubles quite a few students. I have listed the common mistakes that some of my students make and I have also summarized some key concepts. I hope this is of help.

Mark
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banona Senior | Next Rank: 100 Posts
Joined
30 Dec 2006
Posted:
38 messages
1
Wed Feb 14, 2007 7:06 am
Hi Mr Mark Dabral,
It took me 10s to do it, (answer is D)
iI just multiplied the numerator and the denominator by 2^3
and got the amount equivalent to ( 2^3 + 2^4 + 1)/( 1 + 2^2) which equals to ( 8+16+1)/(1=4) = 25/5 = 5

I hope I am right

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