An experiment was conducted to determine the effectiveness of a method designed to remove oil wastes found in soil.Three contaminated soil samples were treated.After 95 days,the percentage of contamination removed from each soil sample was measured,with a mean of 49.3 percent and a standard deviation of 1.5 percent.If we wished to narrow the boundary around μ for a 98 percent confidence interval to within 0.5 percent,how many soil samples should be in our experiment.
A) 437
B) 33
C) 9
D) 6
E) 3

Question

Quizplus · Accepted Answer

To narrow the confidence interval to within 0.5 percent with a 98% confidence level, we use the formula for the sample size: n = (Z*σ/E)^2. Here, Z for 98% confidence is approximately 2.33, σ is 1.5, and E is 0.5. Plugging these values in gives n ≈ 437.

An Experiment Was Conducted to Determine the Effectiveness of a Method