Use the Fundamental Counting Principle to find the size of the sample space: $\displaystyle{6}\cdot{6}\cdot{2}={72}\usepackage{cmbright}\Huge\$

The event space is {(1, 1, H), (2, 2, H), (3, 3, H), (4, 4, H), (5, 5, H), (6, 6, H)}.

The size of the event space is 6. The probability is: $\displaystyle\frac{{6}}{{72}}=\frac{{1}}{{12}}\usepackage{cmbright}\Huge\$