Problem-Solving and Data AnalysisMediumWider interval at a higher confidence level
Problem-Solving and Data Analysis practice question
From one random sample, a researcher computed a 90% confidence interval of 40 to 46 grams for a population mean. Which of the following could be the 95% confidence interval computed from the SAME sample?
- A. 39 to 47 gramsCorrect
- B. 41 to 45 grams
- C. 40 to 46 grams
- D. 44 to 50 grams
Answer: A. 39 to 47 grams
Higher confidence needs a wider interval around the same centre (43). Only 39 to 47 is wider and centred at 43.
Why the other answers are wrong
- B. 41 to 45 grams
- 41 to 45 is NARROWER, which would correspond to a lower confidence level.
- C. 40 to 46 grams
- The same width can't correspond to two different confidence levels.
- D. 44 to 50 grams
- 44 to 50 is centred at 47, but the same sample gives the same centre, 43.
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