Expert: Paul Klarreich - 1/26/2012

Question
QUESTION: I substitute teach a few days a week and have been trying to figure out how to determine the average time I receive the telephone call. This would be easy if I got called every day but there are days when I don't get called. Example: say I get called Monday at 5.30am, Tuesday at 6am, Wednesday at 6.15am, Thursday at 7am but Friday I get no call. The possible range of call times is from 5.30am - 8.30am Monday-Friday. How do I figure the average call time for the example?

ANSWER: Questioner:David
Subject:averages
Question:

I substitute teach a few days a week and have been trying to figure out how to determine the average time I receive the telephone call. This would be easy if I got called every day but there are days when I don't get called. Example: say I get called Monday at 5.30am, Tuesday at 6am, Wednesday at 6.15am, Thursday at 7am but Friday I get no call. The possible range of call times is from 5.30am - 8.30am Monday-Friday. How do I figure the average call time for the example?
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An average that includes such a 'non-call' is probably meaningless, BUT:  If you have decided how to use the average, that may help you answer this.  If you get (somehow) an average of 5:42 A.M., then what will you do with it?

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QUESTION: Interesting answer. As a follow-up I am using this chart with averages, but I don't know how to enter the numbers as time rather than quantity. In other words, when I enter the call times (e.g. 5.50) the averages box at the bottom of the chart reads it as 5 1/2 rather than 10 minutes before 6. Would you know how to make the chart so that it reads as time rather than quantity?

Answer
I substitute teach a few days a week and have been trying to figure out how to determine the average time I receive the telephone call. This would be easy if I got called every day but there are days when I don't get called. Example: say I get called Monday at 5.30am, Tuesday at 6am, Wednesday at 6.15am, Thursday at 7am but Friday I get no call. The possible range of call times is from 5.30am - 8.30am Monday-Friday. How do I figure the average call time for the example?
.................................................
An average that includes such a 'non-call' is probably meaningless, BUT:  If you have decided how to use the average, that may help you answer this.  If you get (somehow) an average of 5:42 A.M., then what will you do with it?

---------- FOLLOW-UP ----------

QUESTION: Interesting answer. As a follow-up I am using this chart

>>> I see -- you are a NON-math substitute teacher.  Math teachers never use charts, only tables.
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with averages, but I don't know how to enter the numbers as time rather than quantity. In other words, when I enter the call times (e.g. 5.50)

>> That's easy --  5:50 is 5 and 5/6 hours, which you can use your (Windows) calculator to write as  5.833.


the averages box at the bottom of the chart reads it as 5 1/2 rather than 10 minutes before 6. Would you know how to make the chart so that it reads as time rather than quantity?