[tex]\text{probability}=\frac{\text{ number of favorable cases}}{total\text{ number of cases}}[/tex][tex]\text{ P(red shorts)=}\frac{8}{4+6+2+8+3+7}=\frac{8}{30}=\frac{4}{15}[/tex][tex]\text{ P(shirt or white)=}\frac{4+6+2+7}{4+6+2+8+3+7}=\frac{19}{30}[/tex]
(Notice that, in the last case, there are 2 cases that satisfy both criteria at the same time, that is, there are 2 white shirts; you don't have to add it twice, that is why in the numerator there is only one 2)
