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

[BTGModeratorVI]

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

Answer: A
Source: Kaplan

[Brent@GMATPrepNow]

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

Answer: A
Source: Kaplan

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