Kathy is deciding on her schedule for next semester. She must take each of the following classes: English 101, Music 101, Biology 102, and Math 120. If there are 16
sections of English 101, 10
sections of Music 101, 13
sections of Biology 102, and 15
sections of Math 120, how many different possible schedules are there for Kathy to choose from? Assume there are no time conflicts between the different classes.