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Problem-Solving and Data AnalysisHardWhich sample mean to trust more

Problem-Solving and Data Analysis practice question

Two random samples of households were taken from the same town to estimate the town's mean weekly grocery spending. Sample 1 had 100 households and a mean of $141. Sample 2 had 400 households and a mean of $139. Which sample's mean is more likely to be close to the town's true mean, and why?

  1. A. Sample 2, because a larger random sample has less sampling variability.Correct
  2. B. Sample 1, because its mean is higher.
  3. C. Sample 1, because a smaller sample is easier to measure accurately.
  4. D. Neither, because the two means are different.

Answer: A. Sample 2, because a larger random sample has less sampling variability.

Larger random samples give estimates that vary less from the population value.

Why the other answers are wrong

B. Sample 1, because its mean is higher.
A higher mean is not a more accurate one.
C. Sample 1, because a smaller sample is easier to measure accurately.
Ease of measurement does not reduce sampling variability.
D. Neither, because the two means are different.
Sample means always differ a little; the larger sample is still more reliable.

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