(i)[5]
Apply a normal approximation to determine the probability that the number of days on which Wenjie goes out with her friends is below 30 or above 44.
(ii)[1]
Give a reason to show that the use of a normal approximation is justified.
Mathematics 9709 · AS & A Level · Continuous random variables
Continuous random variables — practice question
The chance that Wenjie goes out with her friends on a given day is $\frac{1}{7}$. 252 days are selected at random.
Worked solution & mark scheme
This 6-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Correct calculation of $np = 252 \times \frac{1}{7} = 36$ and $npq = 252 \times \frac{1}{7} \times \frac{6}{7} = 30.857$” …
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