An Experiment Was Conducted to Determine the Effectiveness of a Method

Multiple Choice

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% and a standard deviation of 1.5%.If we wished to narrow the boundary around $\mu$ for a 98% confidence interval to within 0.5%,how many soil samples should be in our experiment.

A) 437
B) 33
C) 9
D) 6
E) 3