The cost of Brand V paper is proportional to the weight

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BTGmoderatorDC: Moderator; Posts: 7187; Joined: Thu Sep 07, 2017 4:43 pm; Followed by:23 members

The cost of Brand V paper is proportional to the weight

by BTGmoderatorDC » Tue Jan 09, 2018 11:39 pm

The cost of Brand V paper is proportional to the weight. If 18 ounces of Brand V paper cost $ 3.06, what is the cost of 24 ounces of Brand V paper?

A. $4.08
B. $5.58
C. $6.12
D. $7.31
E. $7.59

Can some experts show me the easiest and fastest solution in this problem?

OA A

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Source: Beat The GMAT — Problem Solving | Tue Jan 09, 2018 11:39 pm

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by [email protected] » Wed Jan 10, 2018 5:13 pm

Hi lheiannie07,

We're told that the cost of Brand V paper is proportional to the weight and that 18 ounces of Brand V paper cost $ 3.06. We're asked for the cost of 24 ounces of Brand V paper. This question can be approached in a number of different ways, but you can set up a ratio and get to the correct answer with a bit of estimation.

Since the cost of the paper is PROPORTIONAL to the weight, the question is essentially telling you to think about ratios. You can set up a ratio in several different ways, but the one that's most beneficial is....

18/24 = $3.06/X

Instead of immediately cross-multiplying, you should simplify the fraction first...

3/4 = $3.06/X

Now you have "3 is to 4" as "a-little-more-than 3 is to....". The only possibility is "a-little-more-than 4." There's only one answer that matches...

Final Answer: A

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

Contact Rich at [email protected]

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Scott@TargetTestPrep: GMAT Instructor; Posts: 8086; Joined: Sat Apr 25, 2015 10:56 am; Location: Los Angeles, CA; Thanked: 43 times; Followed by:29 members

by Scott@TargetTestPrep » Tue Jan 16, 2018 5:01 pm

lheiannie07 wrote:The cost of Brand V paper is proportional to the weight. If 18 ounces of Brand V paper cost $ 3.06, what is the cost of 24 ounces of Brand V paper?

A. $4.08
B. $5.58
C. $6.12
D. $7.31
E. $7.59

We can create the equation in which k is the unit cost per ounce:

18k = 3.06

k = 0.17

Thus, 24 ounces costs 24 x 0.17 = 4.08 dollars.

Alternate Solution:

We can set up a proportion and solve for x, as follows:

18/3.06 = 24/x

18x = 73.44

x = 4.08

Answer: A

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