The size of the sample space is 20, because there are 20 possible tiles to choose from.

List the event space for Thao winning a point: {4, 8, 12, 16, 20}

List the event space for Andy winning a point: {5, 10, 15, 20}

The probability of Thao drawing a winning tile is $\displaystyle\frac{{5}}{{20}}\usepackage{cmbright}\Huge\$ , or $\displaystyle\frac{{1}}{{4}}.\usepackage{cmbright}\Huge\$

The probability of Andy drawing a winning tile is $\displaystyle\frac{{4}}{{20}}\usepackage{cmbright}\Huge\$ , or $\displaystyle\frac{{1}}{{5}}\usepackage{cmbright}\Huge\$ , which is smaller.