Probability Practice Test 1

Probability of drawing both pink balls ${=}^6{\mathit{C}}_2=\frac{6\times 5}{2\times 1}=15$
Probability of drawing both yellow balls = 15
Probability of drawing two balls ${=}^{12}{\mathit{C}}_2=\frac{12\times 11}{2\times 1}=66$
Probability of drawing both balls of the same colour $=\frac{2\times 15}{66}=\frac{5}{11}$
So, probability of drawing both the balls ofdifferent colours $=1-\frac{5}{11}=\frac{6}{11}.$