Bunuel
On a certain day, a coffee shop started selling a batch of freshly baked cookies at a price 20 percent higher than the shop's cost per cookie, selling 3/5 of them at that price. By noon, due to high demand, the shop increased the price by an additional 25 percent and sold half of the remaining cookies at the new price. In the evening, to clear out the rest, the shop reduced the price by 20 percent and sold 3/4 of the remaining cookies. What was the coffee shop's gross profit from the sale of the cookies as a percentage of its total cost for the batch of baked cookies on that day?
A. 18%
B. 20%
C. 25%
D. 26 6/19%
E. 30%
Say there are 100 cookies.
60 are sold at 20% profit
20 (half of remaining 40) are sold at effective profit of 20 + 25 + 20*25/100 = 50% profit
(Using successive percentage formula discussed here:
https://anaprep.com/arithmetic-successi ... e-changes/ )
15 (3/4th of remaining 20) are sold at effective profit of 50 - 20 - 50*20/100 = 20% profit
5 are sold at 100% loss
Total profit % =\( \frac{75*20 + 20*50 + 5*(-100))}{100} = 20\)%
(Using weighted averages discussed here:
https://www.youtube.com/watch?v=_GOAU7moZ2Q )
Answer (B)