 Solution

ID: past-exam-of-the-mathematics-course-of-the-year-1-of-the-natural-sciences-course-of-the-university-of-cambridge/2011/paper-1/12/a/solution

Write

\overset{s}{ˉ} > 0

1/ \overset{s}{ˉ}

f_{S} (s) = {\overset{s}{ˉ}^{- 1} e^{- s / \overset{s}{ˉ}}, 0, s \geq 0, s < 0.

The density has units of inverse minutes, ensuring that its integral is a dimensionless probability.

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