Mathematics 9709 · AS & A Level · Continuous random variables
Continuous random variables — practice question
The packet weights for one particular type of biscuit are assumed to be normally distributed, with mean 400 grams and standard deviation $\sigma$ grams.
(i)[4]
From a random sample of 6000 packets of this biscuit type, 225 packets had a weight above 410 grams. Determine the value of $\sigma$.
(ii)[4]
In a random sample of 500 packets of this type of biscuit, how many packets would you expect to have weights that lie more than 1.5 standard deviations from the mean?
Worked solution & mark scheme
This 8-mark question has a full step-by-step worked solution and mark scheme.