A box contains 10 black,5 red and 4 green marbles. 3 marbles are drawn from the box at random. What is the probability that all the three marbles are of the same color?  Choose the correct choice from the following options:
A) 143/969
B) 134/969
C) 120/969
D) 19/969
E) 120/134
Explanation:   Total marbles in a box = 10 black + 5 red + 4 green marbles = 19 marbles   3 marbles are drawn from 19 marbles at random. Therefore,   n(S) = 19C3= 969 ways   Let A be the event that 2 marbles drawn at random are of the same color. Number of cases favorable to the event A is   n(A) = 10C3+ 5C3 + 4C3 = 120 +10 + 4= 
<gadget id="calculator">120 +10 + 4</gadget>
<output>134</output>
134   Therefore, by definition of probability of event A,   P(A)= n(A)/n(S) = 134/969   ANSWER:134/969
<result>B</result>
A box contains 10 black,5 red and 4 green marbles. 3 marbles are drawn from the box at random. What is the probability that all the three marbles are of the same color?