The weights ( in pounds) of a sample of five boxes being sent by UPS are :12,6,7,3, and 10. Compute the standard deviation.

I'm not quite sure where to start with this problem What formula do I use for this problem?

Stats: What is a standard deviation?

First you need to find the mean (add them all up and divide by how many there are). In this case, it's equal to 7.6lb.

Secondly, you take each individual value, and find the difference between it and the mean, square it, and add the results together

i.e. (12-7.6)^2 + (6-7.6)^2 + (7-7.6)^2 + (3-7.6)^2 + (10-7.6)^2.

This gives 49.2.

Divide this by "how many you've got" i.e. 5.

This is 9.84.

This is called the variance. To obtain the standard deviation, you just square root the variance, giving you about 3.14.