Average scores for a test taken before learning the topic, then the results following:

Before |12|18|25| 9 |14|16|

After |18|24|24|14|19|20|

The problem is: Construct a 95% confidence interval for μd.

At the 1% significance level, can we conclude that the mean scores increase in the after category?

I think I use the equation d +or- t* sd/sqrt n

∑dsquared=?

∑d=?

n=6

df=5

C.I.=95

alpha=.05

I'm not sure if I'm doing it right any help would be greatly appreciated! I have an example of a similar one but I just want to know for sure if I'm on the right track. Thanks!