PSAT Math Multiple-Choice Question 753: Answer and Explanation

Question: 753

Assume that a scientist is able to measure the average weight of lobsters within a 50-mile radius of an island with a confidence level of 90% by collecting data from 100 random spots around the island. If he wishes to increase the confidence level in his results to 95%, what would best help him achieve his goal?

• A. Compare the results to those from another island 300 miles away.
• B. Expand the radius of sampling to 100 miles and redistribute his 100 random spots within the larger range.
• C. Increase the number of data samples.
• D. Use a scale with 5% more accuracy.

Correct Answer: C

Explanation:

(C) The best way to increase a confidence level is to increase the amount of relevant sample data. A more accurate scale could be of minor help but not as much as increasing the overall data samples. Choices (A) and (B) would provide irrelevant and less accurate data, respectively.