Mathematics 9709 · AS & A Level · Sampling and estimation
Sampling and estimation — practice question
Annan has created a fresh logo for a sportswear company. A survey of many customers showed that $42\%$ of customers judged the logo to be good.
(a(i))[3]
A random sample of $10$ customers is selected. Find the probability that fewer than $8$ of them judge the logo to be good.
(a(ii))[3]
At a different time, a random sample of $n$ customers from the company is chosen. Find the smallest value of $n$ for which the probability that at least one person rates the logo as good is greater than $0.995$.
Worked solution & mark scheme
This 6-mark question has a full step-by-step worked solution and mark scheme. One marking point: “A suitable binomial form is $1-\big(\binom{10}{2}0.42^2 0.58^8 + \binom{10}{1}0.42^1 0.58^9 + 0.42^{10}\big)$.” …