A Test of Abstract Reasoning Is Given to a Random

Multiple Choice

A test of abstract reasoning is given to a random sample of students before and after they completed a formal logic course. The results are given below. Construct a 95% confidence interval for the mean difference between
The before and after scores. $$\begin{array} { | l l l l l l l l l l l | } \hline \text { Before } & 74 & 83 & 75 & 88 & 84 & 63 & 93 & 84 & 91 & 77 \\\hline \text { After } & 73 & 77 & 70 & 77 & 74 & 67 & 95 & 83 & 84 & 75 \\\hline\end{array}$$

A) $1.2 < \mu _ { d } < 8.7$
B) $0.8 < \mu _ { d } < 6.6$
C) $1.0 < \mu _ { d } < 6.4$
D) $0.2 < \mu _ { d } < 7.2$