GMAT Practice Question: On a certain day, a bakery produced a batch of rolls at a total production cost of 300 dollars....
Question
On a certain day, a bakery produced a batch of rolls at a total production cost of 300 dollars. On that day, 4/5 of the rolls in the batch were sold, each at a price that was 50 percent greater than the average (arithmetic mean) production cost per roll. The remaining rolls in the batch were sold the next day, each at a price that was 20 percent less than the price of the day before. What was the bakery's profit on this batch of rolls?
- $150
- $144
- $132
- $108
- $90
Topics: word problems, percentages, revenue/cost, mean, relative changes, translations
Solution
Step 1
We let N be the total number of rolls and c the average production cost per roll.
c = 300/N
Step 2
We translate "4/5 of the rolls in the batch were sold" into the expression for the rolls sold on day one.
4/5N
Step 3
We express the selling price on day one as 50% greater than the cost per roll.
1.5 c
Step 4
We compute the revenue on day one by multiplying the number of rolls sold by the day one price and substituting for c.
R_1 = 4/5N 1.5 c = 4/5N 1.5 300/N = 360
Step 5
We translate "20 percent less than the price of the day before" into the selling price on day two.
p_2 = 0.8 (1.5 c) = 1.2 c
Step 6
We compute the revenue on day two by multiplying the remaining rolls by the day two price and substituting for c.
R_2 = 1/5N 1.2 c = 1/5N 1.2 300/N = 72
Step 7
We find the profit by subtracting the total production cost from the total revenue.
Profit = (360 + 72) - 300 = 432 - 300 = 132
Answer
The bakery’s profit was 132, so the correct answer is C.
