Mathematics 9709 · AS & A Level · Sampling and estimation
Sampling and estimation — practice question
Across the long-distance flights Julian takes, he travels in economy class on $82\%$ of them, and in first class for the remainder. If he is in economy class, the probability that he enjoys a good night's sleep is $x$. If he is in first class, the probability that he enjoys a good night's sleep is $0.9$.
(i)[2]
Draw a tree diagram that is fully labelled to show this situation.
(ii)[2]
The chance that Julian gets a good night's sleep on a flight chosen at random is $0.285$. Find the value of $x$.
(iii)[3]
Given that Julian does not get a good night's sleep on a particular flight, find the probability that he is flying economy class.
(c(iii))[3]
Given that Julian does not get a good night’s sleep on a particular flight, find the probability that he is travelling in economy class.
Worked solution & mark scheme
This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Tree diagram with the correct structure and at least four correct probabilities, including $x$” …