Math A probabilty question

Question

In Year 11 maths A there are three classes with 28,25 and 13 students in them respectively. A committee of three students is to be chosen. one from each class to represent a Maths Task Force. In how many ways can this group of three people be chosen?

Would be much apreciated!!

Answer 1

You pick one from class 1 (28 options), one from class 2 (25 options), and one from class 3 (13 options). So it's just

$$28*25*13=9100$$

different possible teams.

Answer 2

$\binom {25} {1}\binom {28} {1}\binom {13} {1}$

Answer 3

You may choose $1$ from each class, containing $28,25,13$ students, implying that the possible number of different teams are $${25\choose1}{28\choose1}{13\choose1}=9100$$ This can equivalently be written as $25\times 28\times 13$, since you may choose $1$ from each class, containing $28,25,13$ students.