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Find the probability that the total profit earned in a randomly selected $7$-day week is less than $\$22\,000$.
Mathematics 9709 · AS & A Level · Linear combinations of random variables
Linear combinations of random variables — practice question
The mass, in tonnes, of steel made each day at a factory is normally distributed with mean $65.2$ and standard deviation $3.6$. It may be assumed that the amount of steel produced on one day is independent of the amount produced on any other day. The factory earns $\$50$ profit for each tonne of steel produced.
Worked solution & mark scheme
This 6-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Correct mean from the mass values: $7 \times 65.2 = 456.4$” …
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