Question

They learn that a big concert is scheduled for the same night and attendance will be down $25\%.$ How many recipes of cookies should they make for their smaller party?

$6$

$8$

$9$

$10$

$11$

Answer: E

Concepts:percentage floor and ceiling functions

Difficulty rating: 1310

Solution:

There will now only be $108 \cdot \left(1 - \dfrac{1}{4}\right) = 108 \cdot \dfrac{3}{4} = 81$ people at the party. This means we need $\left\lceil \dfrac{81 \cdot 2}{15} \right\rceil = \left\lceil \dfrac{162}{15} \right\rceil = 11$ recipes.

Thus, E is the correct answer.

1999 AMC 8 Problem 18

Answer: E

Difficulty rating: 1310

Solution:

Problem 18 in Other Years