Heather is trying to decide what classes to take next year.

Question

Heather is trying to decide what classes to take next year. She must take one of each and can choose from 3 math classes, 2 science classes, 4 history classes, and 3 English classes. How many different schedules can she have?
A) 4
B) 12
C) 48
D) 72

Answer 1

For combination problems like these, in which order does not matter, you simply multiply the numbers together.

To check the procedure, you can make and solve a similar, easier example: How many schedules with only 3 math classes and 2 science classes to choose from? We can write out all the possibilities. Let's call the 3 math classes 1, 2, 3, and the the two science classes will be A and B. Heather can have A1, A2, A3, B1, B2, B3. That's 6 possible schedules, showing us that we can multiply 3 and 2 to get the answer. So this simpler example tells us that the procedure of multiplying the numbers together for the original problem is correct.