While training for a triathlon, Trina will first swim, then cycle and finally run. She will swim either 200, 300, 400 or 500 metres, followed by cycling 5, 9, or 13 kilometres, and finally running either 2 or 3 kilometres. How many different possible choices of training routines does Trina have?

swimming has 4 choices

cycling has 3 choices
running has 2 choices

4 x 3 x 2 = 24 possible routines.

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- Calvin Lin
Brilliant Challenge Master

To find the number of different possible choices of training routines, we need to multiply the number of options for each activity together.

First, let's calculate the number of options for each activity:

For swimming, Trina has 4 options (200, 300, 400, or 500 meters).
For cycling, Trina has 3 options (5, 9, or 13 kilometers).
For running, Trina has 2 options (2 or 3 kilometers).

To find the total number of different training routines, we multiply these numbers together:

4 options for swimming × 3 options for cycling × 2 options for running = 4 × 3 × 2 = 24.

Therefore, Trina has 24 different possible choices of training routines.