Question

A pizza restaurant has found that the probability that a customer will order thin crust is 0.4. In a random sample of 5 customers who order a pizza, find the probability that at least three of them want thin crust.

Answer 1

In this type of exercises, the probability of x successes on n reapeted trials in an experiment is given by the next formula:

`P=\text{nCx}\cdot p^x\cdot(1-p)^(n-x)`

Here the nCx indicates the number of different combinations of x objects selected from a set of n objects. With the given data we can solve it easily:

p = 0.4

n = 5

x = 3

`\begin{gathered} P=5\text{C3}\cdot0.4^3\cdot(1-0.4)^(5-3) \\ P=10\cdot0.064\cdot0.36 \\ P=0.2304 \end{gathered}`