how to calculate average

Question

hallo Valpes

i have a datagrid on visual studio2008. I have aprocedure to call it to dgv1.on selection of combobox1 the selected item is then displayed on dgv1.
I need to work out the average of three columns and name it respectively.and display in dgv2 or in same dgv1 with new colums.

dist	time	spd	name
1200	59.63	16.26	shanny
1400	65.23	15.89	shanny
1600	80.10	14.23	shanny

 i need average for 1.2.3 please