0 = 1
1 = 6
2 = 4
3 = 5
4 = 3
5 = 6
6 = 3
7 = 2
8 = 1
9 = 2
(HOURS)

In my statisticsassignment I asked students from the ages 15-18 about how much time they spend on the internet per day.

1) Compute the average value (average time spent on the internet).
2) Replace each value by the square of the difference between that value and the average value.
3) Compute the new average value.
4) Take the square root of that new average value.

If you're still working on statistics I've got an excel spreadsheet that is setup to take your sample (N) and calculate standard deviation as described above. Also gives you your mean, median, low, high and a few others. Send PM I'll hook you up.