Calculation of Probability value using Poisson Distribution

"An internal study by the Technology Services department at Lahey Electronics revealed company employees receive an average of two emails per hour. Assume the arrival of these emails is approximated by the Poisson distribution. a. What is the probability Linda Lahey, company president, received exactly 1 email between 4 P.M. and 5 P.M. yesterday? b. What is the probability she received 5 or more email during the same period? c. What is the probability she did not receive any email during the period? "