Question

At the beginning of the school year, Lisa's goal was to earn an A on at least $80\%$ of her $50$ quizzes for the year. She earned an A on $22$ of the first $30$ quizzes. If she is to achieve her goal, on at most how many of the remaining quizzes can she earn a grade lower than an A?

$1$

$2$

$3$

$4$

$5$

Answer: B

Concepts:percentage inequality

Difficulty rating: 960

Solution:

Lisa needs an A on at least $0.8 \cdot 50 = 40$ quizzes.

She already has $22,$ so she needs $40 - 22 = 18$ A's among the remaining $20$ quizzes.

That leaves at most $20 - 18 = 2$ quizzes with a grade lower than an A.

Thus, B is the correct answer.

2005 AMC 10B Problem 6

Answer: B

Difficulty rating: 960

Solution:

Problem 6 in Other Years