I need some help on homework, specifically math

This is regarding a gr.7 Mathematics question.

Explain which event is more likely:

-rolling two dice and getting a total of 11

or

-tossing a coin and getting three Heads in a row

rolling the dice you could roll a 5 and a 6

tossing a coin is a 1/2 x 3

so your odds are 1/12 against 3/6
.....i think it's obvious

rolling two dice and getting a total of 11: 2/36 = 1/18

tossing a coin and getting three heads in a row: (1/2)^3 = 1/8

too easy...why can't you do this ?