Problem Solving

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

Can some experts show me the simplest way to solve this problem?

OA A

We are given that the cost of Brand V paper is proportional to the weight.

It means that if the weight of the paper doubles, its cost doubles; if the weight increases by 50%, its cost increases by 50%, and so on.

The given data is for the weight 18 ounces and we are asked to determine the cost of 24-ounce paper. We see that the weight of the 24-ounce paper is (24/18)*100% = (400/3)% of the 18-ounce paper. Thus, the cost of the 24-ounce paper would also be (400/3)% of the 18-ounce paper.

The cost of the 24-ounce paper = (400/3)% of the 18-ounce paper

The cost of the 24-ounce paper = (400/3)% * 3.06 = (400*1.02)/100 = $4.08.

The correct answer: A

Hope this helps!

-Jay
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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

Since cost is PROPORTIONAL to weight, we can use EQUIVALENT RATIOS

We'll compare cost/weight
Let x = the cost of 24 ounces of paper

So, we get: 3.06/18 = x/24
Cross multiply to get: (18)(x) = (24)(3.06)
Divide both sides by 18 to get: x = (24)(3.06)/18

ASIDE: From here, we can use estimation to find the value of x.
Notice that (24)(3.06) is a little bit bigger than (24)(3)
So, (24)(3.06) = a little bit bigger than 72, which we can denote as 72+

We get: (24)(3.06)/18 = 72+/18
= 4+ (a number a little bit bigger than 4)

Answer: A

Cheers,
Brent