1. If a data set has 25 values and a standard deviation 8.4, then the variance is ________.
2. Adrian claims that his new training methods have improved his battingaverage. Before starting his new regimen, he was batting 0.220 in a random sample of 50 bats. For a random sample of 24 at bats since changing his training technique, his batting average is 0.375.

Determine if there is sufficient evidence to say that his batting average has improved at the 0.10 (10%) level of significance. Compute the test statistic, Construct an appropriate confidence interval, does Adrian appear to have improved at batting?