Question

A survey finds that customers are charged incorrectly for 1 out of every 30 items, on average. Suppose a customer purchases 12 items. Find the following probability. A customer is not charged incorrectly for any item. The probability is . (Round to four decimal places as needed.)

Answer 1

Given,

Probability of charging a customer incorrectly, p = 1/30 = 0.0333

Let x be a random variable which represents the number of items charged incorrectly.

we know that,

$\small P(X=x) = \binom{n}{x}p^{x}(1-p)^{n-x}$

Required probability P(X=0)

$\small P(X=0) = \binom{12}{0}*0.033^{0} *(1-0.033)^{12-0}$

$\small P(X=0) = 0.6658$

Therefore,

The probability is 0.6658