Topic Questions: • use, when solving problems, the results that – $\mathrm{E}(aX+b)=a\mathrm{E}(X)+b$ and $\mathrm{Var}(aX+b)=a^2\mathrm{Var}(X)$ – $\mathrm{E}(aX+bY)=a\mathrm{E}(X)+b\mathrm{E}(Y)$ – $\mathrm{Var}(aX+bY)=a^2\mathrm{Var}(X)+b^2\mathrm{Var}(Y)$ for independent $X$ and $Y$ – if $X$ has a normal distribution then so does $aX+b$ – if $X$ and $Y$ have independent normal distributions then $aX+bY$ has a normal distribution – if $X$ and $Y$ have independent Poisson distributions then $X+Y$ has a Poisson distribution — 9709 P6 Linear combinations of random variables

Topic question rules and edge cases

How many topic questions cover this syllabus point?

64 question stems cover this subtopic across 40 papers, but only 90 tagged parts and 375 marks belong to it. Other parts of the same questions are assessed under different statements and are excluded from this page.

Which papers include this subtopic?

The table lists every matching session from 2020–2026. Each row links to the question anchor on the paper page, where the full paper context and practice entry point are available.

Why can one question appear under several subtopics?

The parts of one question can assess different syllabus statements. Each part is counted under its own subtopics, so the same question stem can appear on several subtopic pages while each page lists only the parts and marks tagged to that statement.

Can I practise these questions with AI marking?

Yes. Open a paper from the table and use the Interactive Practice Hub entry point. The page itself is static HTML so search engines and retrieval agents can read the full question list without executing JavaScript.