need help in this probability and statistic question with steps, thank you

4. [10 points] A sales manager receives 6 telephone calls on average between 9 : 30am and 10 : 30am on a weekday. Find the probability that (a) the manager will receive 2 or more calls between 9 : 30am and 10 : 30am on a certain weekday. (b) the manager will receive exactly 2 calls between 9 : 30am and 9 : 40am. (c) during a normal 5-day working week, there will be exactly 3 days on which the manager will receive exactly three calls between 9 : 30am and 9 : 40am