2021 AMC 12B Spring Problem 4
Attempt Problem 4 of the 2021 AMC 12B Spring below, then check your answer against the professionally curated solution from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2021 AMC 12B Spring solutions, or check the answer key.
All problems are used with official legal permission of the Mathematical Association of America (MAA).
4.
Ms. Blackwell gives an exam to two classes. The mean of the scores of the students in the morning class is and the afternoon class’s mean score is The ratio of the number of students in the morning class to the number of students in the afternoon class is What is the mean of the scores of all the students?
Answer: C
Small hint:
Take students in the morning and in the afternoon
Big hint:
The overall mean is
Solution:
Suppose there are students in the morning class and in the afternoon class.
The total of all scores is
The overall mean is
Thus, the correct answer is C.
Problem 4 in other years
- 1950 AMC 12
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