AAPL wrote:GMAT Prep
A certain candy manufacturer reduced the weight of Candy Bar \(M\) by 20 percent but let the price unchanged. What was the resulting percent increase in the price per ounce of Candy Bar \(M\)?
A. 5%
B. 10%
C. 15%
D. 20%
E. 25%
OA E
We are given that a certain candy manufacturer reduced the weight of Candy Bar M by 20 percent but left the price unchanged. If we let w = the original weight of the bar, the new weight is 0.8w = 4w/5. If we let p = the original price of the bar we know:
p/w = the original price per ounce of the bar
p/(4w/5) = 5p/4w = the new price per ounce of the bar
Finally we can determine the resulting percent increase in the price per bar due to the change:
[5p/4w - p/w]/[p/w] x 100
[5p/4w - 4p/4w]/[p/w] x 100
[p/4w]/[p/w] x 100
p/4w x w/p x 100 = 1/4 x 100 = 25%
Alternate Solution:
Let's assume the candy bar's original weight was 20 ounces, and its cost was $1.60. Thus, its original cost per ounce was $0.08, or 8 cents.
The new candy bar weighs 20 x 0.8 = 16 ounces, and its cost is unchanged, so it is still $1.60. Thus, the cost per ounce of the new candy bar is $0.10, or 10 cents.
We calculate the percent increase, using the formula: (New - Old)/Old x 100 to obtain:
(10 - 8)/8 x 100 = 0.25 x 100 = 25%.
Answer: E
