1952 AMC 12 Problem 2

Attempt Problem 2 of the 1952 AMC 12 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 1952 AMC 12 solutions, or check the answer key.

All problems are used with official legal permission of the Mathematical Association of America (MAA).

Two high school classes took the same test. One class of

20

students made an average grade of

80\%

; the other class of

30

students made an average grade of

70\%.

The average grade for all students in both classes is:

75\%

74\%

72\%

77\%

None of these

Weight each class average by the number of students in that class

The combined average is

\dfrac{20(80)+30(70)}{50}

The two classes earned a combined total of

20(80)+30(70)=3700

percentage points among

50

students. Their combined average is

\frac{3700}{50}=74\%.

Thus, the correct answer is B.

Problem 2 in other years