# Standard Deviation and Variance

Can someone help me with this question because I'm not sure of how to do it exactly:

There are two routes for a worker to get to his office. Both the routes involve hold ups due to traffic lights. He records these times over a series of six journeys for each route. The results are shown below:

Route 1 : 15 15 11 17 14 12

Route 2 : 11 14 17 15 16 11

Work out the standard deviation for each route.

I am confused as I don't know in the formula for standard deviation in a discrete frequency distribution which part would be x and which would be f.

Any help would be great.

• We welcome questions like this, but we treat them differently. I added the [self-study] tag; please read its wiki to understand the process. – gung Oct 11 '14 at 14:33
• Why did you include "variance" in the title? The question doesn't mention it. Can you clarify what you mean by "x" & "f"? Presumably you were given some formula & are having trouble applying it. What do you mean by a "discrete frequency distribution"? It seems to me you were given distributions of times (which are continuous). – gung Oct 11 '14 at 14:35