A random sample of 150 students has an average test score of 86.28. The standard deviation of the entire school is 10.3. Find the margin of error if c = 0.90.

Answer 1

margin of error = z-critical for confidence level (c) * SD/sqrt(sample size)

z-critical for c = 90 is 1.645

so margin of error = 1.645 * 10.3/sqrt(150)