The standard deviation is actually a mathematical representation of how spread out the numbers is. If you need to calculate it, it is the squareroot of the variance. Now variance is basically the average of the squared differences that are calculated from the mean.
Therefore, if we want to calculate the variance, using these two values we simply subtract 6 from 10 and add 6 to ten. This will give us the range over which the actual tolerance lies around the mean. This results in an answer of 4 to 16. This means that the true answer is anywhere from four to 16, 6 units on either side of the mean.