Question

Suppose that X is the number of cars per minute that pass through a certain intersection, and that X has the poisson distribution. If the mean of X is equal to 9 cars, what is the variance of X?

a) 9² cars
b) 9 cars²

Answer 1

The variance of X in a Poisson distribution with a mean of 9 is 9 cars.

Step-by-step explanation:

The variance of a Poisson distribution can be calculated using the formula var(X) = λ, where λ represents the mean of the distribution. In this case, the mean (λ) is equal to 9 cars per minute. Therefore, the variance is also equal to 9 cars.

So, the correct answer is 9 cars (option b).