Political editorial writer Dee Bunker Fish is interested in campaign spending by current members of the state legislature. More specifically, she is interested in the contrast in the spending levels of Republican vs. Democratic members.
Ms. Fish has taken a simple random sample of 14 Republican members of state legislatures and a similar sample of 14 Democratic members. Carefully checking expenditures, Fish found that, in the last election, the Republicans in the sample spent an average of $ 7,800, with standard deviation of $ 1,400, while Democrats spent an average of $ 6,250, with standard deviation of $ 1,100. Build and interpret the 95% confidence interval to estimate the difference in average campaign expenditures for the two populations represented here. (Assume the two population distributions are normal, with equal standard deviations.).