- In a large restaurant an average of 3 out of every 5 customers ask for water with their meal.
A random sample of 10 customers is selected.
- Find the probability that
- exactly 6 ask for water with their meal,
- less than 9 ask for water with their meal.
A second random sample of 50 customers is selected.
- Find the smallest value of \(n\) such that
$$\mathrm { P } ( X < n ) \geqslant 0.9$$
where the random variable \(X\) represents the number of these customers who ask for water.