Mathematics 9709 · AS & A Level · The normal distribution
Find the probability that either all three own an electric car or none of them do.
A random sample of 125 residents of Wimfield is taken. Use a suitable approximation to determine the probability that more than 45 of them own an electric car.
This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Applies $0.3^3 + 0.7^3$ or an equivalent method such as $1 - (3 \times 0.3^2 \times 0.7 + 3 \times 0.3 \times 0.7^2)$” …