Mathematics 9709 · AS & A Level · Continuous random variables

Continuous random variables — practice question

(i)[3]

The amount of soup in Super Soup cartons follows a normal distribution with mean $\mu$ millilitres and standard deviation $9$ millilitres. Testing has shown that $10\%$ of cartons contain under $440$ millilitres of soup. Find the value of $\mu$.

(ii)[3]

A food retailer places an order for $150$ Super Soup cartons. Calculate how many of these cartons you would expect to have a soup volume that is more than $1.8$ standard deviations above the mean.

Worked solution & mark scheme

This 6-mark question has a full step-by-step worked solution and mark scheme. One marking point: The correct $z$-value is $-1.282$ (or $\pm1.282$ shown)

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