A researcher is interested in seeing if negative political ads against an opponent (group one) are more effective than positive ads for the original...

A researcher is interested in seeing if negative political ads against an opponent (group one) are more effective than positive ads for the original candidate (group two). If the mean for group one is 7.00, the mean for group two is 10.00, the n for group one is 20, the n for group two is 20, the variance for group one is 2.50, and the variance for group two is 4.5. What is T? What is the standard deviation?