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At a coding bootcamp, the morning cohort has 18 students with a test average of 76, and the afternoon cohort has 12 students with a test average of 86. What is the average score of all 30 students taken together?
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Correct answer
B
A combined average is a weighted average: total points divided by total students. Morning points are 18 × 76 = 1368 and afternoon points are 12 × 86 = 1032, so the combined total is 1368 + 1032 = 2400 over 30 students, giving 2400 ÷ 30 = 80, choice (B).
The modal trap is (C) 81, the plain midpoint; that would be correct only if the two cohorts were equal in size, but the larger morning cohort pulls the blend below the midpoint, toward 76. Choice (D) 82 swaps the weights onto the wrong cohorts, pairing the morning size with the afternoon average and vice versa.
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