Let be the total amount of money paid by any given set of passengers. If there are
passengers in a car, then the driver must pay a toll of
.
Then has first moment (equal to the mean)
and second moment
Recall that the variance is the difference between the first two moments:
Here's the solution,
The given triangle is a <em><u>Right</u></em><em><u> </u></em><em><u>angled</u></em><em><u> </u></em><em><u>triangle</u></em><em><u>,</u></em>
So, by applying <em><u>Pythagoras</u></em><em><u> </u></em><em><u>theorem</u></em><em><u>:</u></em>
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value of c = 5 miles