SAT One-variable data: distributions and measures of center and spread Practice Question 13 (Hard)

Question bank / One-variable data: distributions and measures of center and spread

Math · Problem-Solving and Data AnalysisHard

The combined mean test score of the students in two classes is $84$ . Class A has $20$ students with a mean score of $78$ , and class B has a mean score of $88$ . How many students are in class B?

Student-produced response: enter your answer.

Show answer and explanation

Answer: 30

Let $n$ be the number of students in class B. The total of all scores is $20(78) + 88n = 84(20 + n)$ . This gives $1560 + 88n = 1680 + 84n$ , so $4n = 120$ and $n = 30$ .

Answering $20$ assumes the classes are the same size, but then the combined mean would be $83$ , the average of $78$ and $88$ .

Ask Owl about this question Next question

Got it wrong? On SAT Owl, Owl looks at the answer you chose and explains the exact mistake, then gives you similar questions until it sticks. Get your predicted SAT score free.