Smarty Pants Tutoring advertises that it can help students improve their ACT test scores. They work with students who have previously taken the ACT and then compare their scores on a second attempt. An SRS of their clients indicates an average gain in the composite scores of 1.7 points with a margin of error of 1.2 points.

What procedure was performed?

Select one:

a.)Two-sample T-Interval

b.)No inference required

c.)One-sample T-Interval

d.)T-Interval for the difference in matched pairs (paired data)