A behavioral economist studies transportation habits in an urban center. She identifies 4 bus routes that connect to 3 different light rail routes available to participants in the study. Before she interviews participants, she must determine the number of possible routes participants can choose to use. Which expression represents the number of available options?

Question

4!+3!

4×3

4!×3!

4!/3!

Answer 1

clearly, 4!x3!
she can pick the 4 bus routes in any order. For each pick, she can assign the rail routes in any order.

Probably not practical in the real world, however...