How many different outcomes are possible if you can choose between a bus or a train, full fare or concession and you can travel in the morning or the afternoon?

3 pairs of choices give rise to 2^3 = 8 possibilities:

... bus, full, morning

... bus, full, afternoon

... bus, concession, morning

... bus, concession, afternoon

... train, full, morning

... train, full, afternoon

... train, concession, morning

... train, concession, afternoon