Question

The probability that a randomly selected box of a certain type of cereal has a particular prize is 0.1. Suppose you purchase box after box until you have obtained three of these prizes. What is the probability that you purchase x boxes that do not have the desired prize?

Answer 1

The probability is 1 - 0.1x

Explanation:

Probability a randomly selected box have the desired prize = 0.1

Probability of purchasing x boxes that have the desired prize = 0.1 × x = 0.1x

Probability of purchasing x boxes that do not have the desired prize = 1 - 0.1x