Answer:
λ=9
Explanation:
The Poisson distribution can be used to model the number of events occurring in a fixed interval of time. In this case, we can use the Poisson distribution to model the number of calls received by the customer service center.
We know that there is an average of 18 calls in a half hour period. Since a half hour is twice as long as a 15-minute period, we can divide λ by 2 to obtain the average number of calls in a 15-minute period.
λ = 18/2 = 9