Solution

ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2002/ia/paper-2/11f/a/solution

For independent random variables, the probability density function of a sum is the convolution of probability densities. Since each density is one on and zero elsewhere,
This is the length of . Therefore the density is
The two triangular areas sum to one, as a probability density function must.

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