A bag contains 4 white, 5 red and 6 blue balls. Three balls are drawn at random from the bag. The probability that all of them are red, is: Choose the correct choice from the following answers:
A) 3/21 B) 2/91 C) 4/91 D) 8/81 E) 9/72
Let S be the sample space.   Then, n(S)	= number of ways of drawing 3 balls out of 15   = 15C3   = (15*14*13)/(3*2*1)= 
<gadget id="calculator">(15*14*13)/(3*2*1)</gadget>
<output>455</output>
455   Let E= event of getting all the 3 red balls   n(E) = 5C3 = 5C2 =(5*4)/(2*1)= 
<gadget id="calculator">(5*4)/(2*1)</gadget>
<output>10</output>
10   P(E)=n(E)/n(S)   = 10/455   = 2/91   Answer should be 2/91
<result>B</result>
A bag contains 4 white, 5 red and 6 blue balls. Three balls are drawn at random from the bag. The probability that all of them are red, is: