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 Question from Andrew, a student: Suppose you own a local pizza restaurant, Pizza with Pizzazz, and in order to compete with the big pizza chains in your area you are considering an advertising campaign offering customers a free pizza if their pizza is not delivered in 30 minutes or less. Even though your pizza restaurant is known for its fast and friendly delivery service, you are not sure if you can afford to give away too many pizzas for free. Looking over your past 12,421 pizza deliveries you find out 97% of the pizzas were delivered in 30 minutes or less. Calculate the probability that all 100 randomly selected pizza deliveries will have been made in 30 minutes or less? Hint: Use the multiplication rule. (Round 4 decimals) I'm really stumped on how exactly to do this problem. I don't need the answer just the steps broken down to show me how to get it! It would be gladly appreciated if you could help!

Hi Andrew,

The subject line of your email suggested that you were expecting to use the Normal Distribution to solve this problem. I don't think you should try to use the Normal Distribution. I expect you are to take the statement "Looking over your past 12,421 pizza deliveries you find out 97% of the pizzas were delivered in 30 minutes or less." to mean that the probability that a pizza is delivered on time is 0.97. I think you are also expected to assume that the pizza deliveries are independent so that the probability of delivering a pizza on time is 0.97 regardless of what has happened on the previous deliveries. This allows you to use the multiplication rule.

Can you complete the problem now? Write back if you need further assistance,
Penny

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