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## Suppose occurrences of sales on a small company's website are well modeled by a Poisson model

Suppose occurrences of sales on a small company's website are well modeled by a Poisson model with lambda = 2/hour

.

a) If a sale just occurred, what is the expected waiting time until the next sale?

b) What is the probability that the next sale will happen in the next 18 minutes?