Annie and Xenas each arrive at a party at a random time between 2:00 and 4:00. Each stays for 45 minutes and then leaves. What is the probability that Annie and Xenas see each other at the party?
The probability that Annie and Xenas see each other at the party is the probability that they arrive at the party within 45 minutes of each other. There are 120 minutes between 2:00 and 4:00, so the probability that they arrive within 45 minutes of each other is 45/120 = 3/8.
+274 
