Question

A random sample of eighty-five students in Chicago city high schools takes a course designed to improve SAT scores. Based on these students, a 90% confidence interval for the mean improvement in SAT scores from this course for all Chicago city high school students is computed as (72.3, 91.4) points. The correct interpretation of this interval is__________.

A. that 90% of the students in the sample had their scores improve by between 72.3 and 91.4 points.B. that 90% of the students in the population should have their scores improve by between 72.3 and 91.4 points.C. Neither choice is correct.

Answer 1

(B) The correct interpretation of this interval is that 90% of the students in the population should have their scores improve by between 72.3 and 91.4 points.

Explanation:

Confidence interval is the range the true values fall in under a given confidence level.

Confidence level states the probability that a random chosen sample performs the surveyed characteristic in the range of confidence interval. Thus,

90% confidence interval means that there is 90% probability that the statistic (in this case SAT score improvement) of a member of the population falls in the confidence interval.