Mathematics 9709 · AS & A Level · Continuous random variables
Continuous random variables — practice question
Peter’s journey to the shop plus the purchase of a newspaper takes a time, measured in minutes, that is normally distributed with mean 9.5 and standard deviation 1.3.
(i)[3]
Find the probability that, on a randomly chosen day, Peter takes longer than 10.2 minutes.
(ii)[3]
On 90% of days he spends more than $t$ minutes. Find the value of $t$.
(iii)[3]
Calculate an estimate of how many days in a year (365 days) Peter takes less than 8.8 minutes to walk to the shop and buy a newspaper.
Worked solution & mark scheme
This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Accurate standardisation of $P(X>10.2)$” …