Browsing as Guest. Progress, bookmarks and attempts are disabled.
Log in to track your work.
June 2012 p62 q3
3078
In Restaurant Bijoux 13% of customers rated the food as ‘poor’, 22% of customers rated the food as ‘satisfactory’ and 65% rated it as ‘good’. A random sample of 12 customers who went for a meal at Restaurant Bijoux was taken.
(i) Find the probability that more than 2 and fewer than 12 of them rated the food as ‘good’.
On a separate occasion, a random sample of n customers who went for a meal at the restaurant was taken.
(ii) Find the smallest value of n for which the probability that at least 1 person will rate the food as ‘poor’ is greater than 0.95.
Solution
(i) Let the random variable \(X\) represent the number of customers who rate the food as ‘good’. \(X\) follows a binomial distribution with parameters \(n = 12\) and \(p = 0.65\). We need to find \(P(2 < X < 12)\).
(ii) Let \(Y\) be the number of customers who rate the food as ‘poor’. \(Y\) follows a binomial distribution with parameters \(n\) and \(p = 0.13\). We need \(P(Y \geq 1) > 0.95\).