The attitudes of a sample of 12 teachers attending a seminar on mathematical problem solving were measured before and after the seminar. A positive number for change in attitude indicates that a teacher's attitude toward math became more positive. The 12 change scores are as follows:

3 ;8 ;1 ;2 ;0 ;5 ;3 ;1 ;1 ;6 ;5 ;2

Using the data set above, calculate:

a.samplemeanx

b.samplevariances

c. samplestandarddeviations