 Solution

ID: past-exam-of-the-mathematical-methods-ii-course-of-the-university-of-oxford/2021-resit/7/b/ii/solution

P (T > t) = e^{- t /25}

for

t \geq 0

. Therefore

P (T > 20) = \int_{20}^{\infty} \frac{1}{25} e^{- t /25} d t = e^{- 20/25} = 0.449 (three significant figures) .

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