Things You'll Need:
- Watch
- Pencil
- Paper
- Calculator
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Step 1
Travel to work and record the time it takes. Start the clock from the time of departure until the time of arrival at your work station. Record the time it takes for a minimum of five days, record additional days to improve on the accuracy.
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Step 2
Calculate the average time it takes to travel to work. Convert minutes into hundreds in order to do the math. Simply, take the number of minutes and divide it by 60. Example 36 minutes = 36/60 or .60. Add up the time for each day and divide it by the number of days.
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Step 3
Take the average and subtract the time for the 1st day. Example, average time to work .60 minutes, the 1st day it took .55 minutes, or .60 -.55 = .05. Record this number on a piece of paper as day 1. Repeat this for each day traveled to work.
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Step 4
Calculate the square for each day. Multiply the difference between the average and actual time for each day by itself. Example .05 x .05 =.0025. Once the square has been determined for each day, add them together to get a total.
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Step 5
Divide the total calculated in step 4 by the number of days with a recorded time minus one. Example: .0006 / (5-1) = .0015.
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Step 6
Calculate the square root of the number from step5. Enter the number in a calculator and hit the SQRT (or symbol for square root) button.
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Step 7
Multiply this value by 3, record this number.
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Step 8
Take the average from step 2 and add the calculated value from step 7, record this number. Then take the average and subtract the calculated value from step 7, record this number.
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Step 9
Convert these two numbers back to minutes by multiplying by 60. Example: .72 x 60 = 42.97 minutes and .48 x 60 = 29 minutes.
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Step 10
You can now be certain that 99.9% of time your travel time will between the two numbers determined in step 9. It will take a minimum of the smaller value, to a maximum of the higher value. In the example, it would take at least 29 minutes, but may take as much as 43 minutes.
