Mathematics 9709 · AS & A Level · Linear combinations of random variables

Linear combinations of random variables — practice question

The masses, in kilograms, of small and large bags of wheat follow the independent distributions $N(16.0, 0.4)$ and $N(51.0, 0.9)$ respectively.

(main)[5]

Find the probability that the total mass of $3$ randomly selected small bags exceeds the mass of one randomly selected large bag.

Worked solution & mark scheme

This 5-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Accurate expectation $E(S_1+S_2+S_3-L)=16\times3-51=-3$” …

Full mark scheme, point by point
Step-by-step worked solution
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