comparison

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comparison

by Ankitaverma » Wed Nov 20, 2013 1:02 pm
Dirt roads may evoke the bucolic simplicity of another century, but financially strained townships point out that dirt roads cost twice as much as maintaining paved roads.

(A) dirt roads cost twice as much as maintaining paved roads
(B) dirt roads cost twice as much to maintain as paved roads do
(C) maintaining dirt roads cost twice as much as paved roads do
(D) maintaining dirt roads costs twice as much as it does for paved roads
(E) to maintain dirt roads costs twice as much as for paved roads.

Q/A-B why not A

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by Mike@Magoosh » Wed Nov 20, 2013 1:15 pm
Ankitaverma wrote:Dirt roads may evoke the bucolic simplicity of another century, but financially strained townships point out that dirt roads cost twice as much as maintaining paved roads.

(A) dirt roads cost twice as much as maintaining paved roads
(B) dirt roads cost twice as much to maintain as paved roads do
(C) maintaining dirt roads cost twice as much as paved roads do
(D) maintaining dirt roads costs twice as much as it does for paved roads
(E) to maintain dirt roads costs twice as much as for paved roads.

Q/A-B why not A
Dear Ankitaverma
I'm happy to respond. :-)
Here's a blog on comparisons in general, with links to other blogs:
https://magoosh.com/gmat/2013/gmat-idioms-of-comparison/

The problem with choice (A) is that it sounds like we are comparing
(a) the cost of dirt roads
vs.
(b) the cost of maintaining paved roads
In other words, it's not an equal-equal comparison. One is the maintenance cost, and the other is the "cost of the road", whatever that means. We know what the sentence is trying to say, but a well-written sentence says exactly what it is trying to say.

Does this make sense?
Mike :-)
Magoosh GMAT Instructor
https://gmat.magoosh.com/

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by [email protected] » Thu Nov 21, 2013 12:26 am
Hi Ankitaverma,

Mike has provided a great explanation for this SC. Since this prompt is based on "Comparisons", and you'll be tested on this rule at least once on the GMAT, here's the simple rule that you need to know:

You MUST compare LIKE things, the number does NOT matter.

You can compare a road to another road.
You can compare a road to several roads.
You can compare the price of a road to the price of another road.

You CANNOT compare a road to a price of another road.

Keep this rule in mind and you'll pick up some easy points on the GMAT.

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Rich
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by guptas » Sat Nov 23, 2013 4:23 pm
Dear Mike,

Why D is not correct? I thought B is comparing maintaining dirt roads with paved roads. Isn't the sentence trying to compare cost to maintain dirt roads with cost to maintain paved roads?

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by [email protected] » Sat Nov 23, 2013 8:29 pm
Hi guptas,

Answer D is not written in "parallel format"; if it was written as this:

"maintaining dirt roads costs twice as much as maintaining paved roads" then it would be acceptable.

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