Question

Suppose Ruth Ann has 3 routes she can travel between the school to the library, and 5 routes from the library to her home. How many routes are there from Ruth Ann’s school to her home with a stop at the library?

9
60
15
25

Answer 1

what did you get?

Answer 2

imagine drawing out a table that has 3 rows and 5 columns

each cell of the table is a possible combo

Answer 3

15

Answer 4

you are correct

Answer 5

See it this way: she has 3 ways to go to the library, say A, B and C
Once she's at the library, she can go in 5 different ways to school, say 1, 2, 3, 4 and 5.

So if she came along B4, you know how her route was.
But this means:
A1, A2, A3, ...
B1, B2, ...
.
.
.
So it means multiplying!