Sir i am stuck on this question

5. It is known that the cups produced by a factory are defective with a probability of 0.01, independently of each other. The factory sells the cups in packs of 10 and returns the money to the customer if more than one Cup in each pack is defective. If a Customer buys 3 packages, what is the probability that only one package will be returned? Don't forget to dene the random variable (5) and their distributions