Need help with this problem asap

#1
1. The average number of calls received by a switchboard in a 30-minute period is 15. What is the probability that between 10:00 and 10:30 the switchboard will receive more than 9 calls but fewer than 15 calls?

2. The average number of calls received by a switchboard in a 30-minute period is 15. What is the probability that between 10:00 and 10:30 the switchboard will receive fewer than 7 calls?

Please help if you can.