Mathematics 9709 · AS & A Level · Continuous random variables
Continuous random variables — practice question
In Pelmerdon, $22\%$ of families have a dishwasher.
(i)[3]
Find the probability that, from $15$ families selected at random in Pelmerdon, the number who own a dishwasher is between $4$ and $6$ inclusive.
(ii)[5]
A random sample of $145$ families is taken from Pelmerdon. Use an appropriate approximation to determine the probability that more than $26$ of them own a dishwasher.
Worked solution & mark scheme
This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Correct binomial expression for $P(X=4,5,6)$ written using $^{15}C_x(0.22)^x(0.78)^{15-x}$” …