Question

Suppose the time it takes a certain printer to print a document is an Exponential random variable with an average time of 15 seconds. You send a document to the printer at 1:00pm, and it is the third document in the queue. What is the probability that your printout will be ready by 1:01pm

Answer 1

0.8046

Explanation:

We're asked to calculate the probability that the job will be ready by 1.01 pm

From the question, we can note that the parameter of an Exponential is E(X)= 15

Next, to calculate the third job probability, we will have to use Poisson Distribution with parameter 1/λ

Therefore, E(Y) = 1/15

Then, The third job will be ready for 1:01 pm, and thus E(Y) = 61/15

Therefore, the required probability is

P(X ≥ 3) = 1 - P(X < 3)

= 1 - Poisson(3,4, true)

= 1 - 0.1954

= 0.8046