Problem-Solving and Data AnalysisHardScaling a sample mean to a population total
Problem-Solving and Data Analysis practice question
A random sample of 40 students at a school with 1,200 students reported a mean of 3.1 hours of homework per week. Based on the sample, what is the best estimate of the total number of hours of homework done per week by all 1,200 students?
Answer: 3720
The sample mean estimates the population mean, so the total is about 3.1 × 1,200 = 3,720 hours.
Common wrong answers
- If you answered 93
- 93 is 3.1 × 30, a slip in the multiplier; there are 1,200 students.
- If you answered 124
- 124 is 3.1 × 40, the total for the SAMPLE only.
- If you answered 387
- 387 is 1,200 / 3.1, dividing instead of multiplying.
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