Solution

ID: past-exam-of-the-mathematics-course-of-the-year-1-of-the-natural-sciences-course-of-the-university-of-cambridge/2019/paper-2/14/c/i/solution

The independence of random variables means that fixing leaves the conditional probability density of equal to . Given that value of , is the translate . Hence
At a continuity point of , the expression is . Since , this conditioning uses a conditional probability density, rather than division by the probability of the single event .

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