How To Work Something Out For a statistics aid for work

[JamboCaz]

Hey All

Sorry if this is the wrong place for this but I need some help to figure out how to solve the following problem.

I am creating a stats aid for some people at my work.

What I need to do is as follows.

Say I have a total of 540 seconds over 20 calls = an average of 27 seconds for this event.

What I am trying to figure out is what calculation to use (I'll be putting this into a spreadsheet) to see how many seconds to make the next call to ensure the average becomes 35 seconds, I can't seem to figure out the reverse.

What I am really trying to do is - I Have a Days Phonecall average and a Days Wrap Time Average and Target Total Average - I am trying to decide what the last calls Wrap time needs to be so I can change the Average Wrap time enough to hit the perfect Target

I hope this makes sense

Please ask me if not

Cheers

Jambo

 

[HallsofIvy]

So you made 20 calls in 540 seconds? Yes, that is an average of 540/20= 27 seconds per call. You want to make one more all that will increase the average to 35 seconds? Call the length of that call "T" seconds. Then you have 21 calls for a total time of 540+ T seconds. The average time per call is, of course, the total time divided by the number of calls: $\displaystyle \frac{540+ T}{21}= 35$. Solve that equation for T.