A box contains 3red, 5yellow and 4 green balls. 3 balls are drawn randomly. What is the probability that the balls drawn contain balls of different colours? Pick
A) 2/7
B) 3/11
C) 1/4
D) 3/7
E) 2/9
Total number of balls = 3+5+4= 
<gadget id="calculator">3+5+4</gadget>
<output>12</output>
12   n(S)= 12C3 = 12*11*10/3*2 = 220 n(E) = 3C1*5C1*4C1 = 3*5*4= 
<gadget id="calculator">3*5*4</gadget>
<output>60</output>
60 P(E)= 60/220 = 3/11 Answer is 3/11
<result>B</result>
A box contains 3red, 5yellow and 4 green balls. 3 balls are drawn randomly. What is the probability that the balls drawn contain balls of different colours?