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A box contains b red balls 2b white 3b blue balls $ b>0 3 balls are selected without replacement if A is the event that no two of the selected balls have same colour then 1) no value of b for which P(A)= 0.3 2) one value of b for which P(A)= 0.3 and this value is less than 10 3) two values of b and this value is greater than 10 4) None

A box contains b red balls 2b white 3b blue balls $ b>0


3 balls are selected without replacement if A is the event that no two of the selected balls have same colour then


1) no value of b for which P(A)= 0.3


2) one value of b for which P(A)= 0.3 and this value is less than 10


3) two values of b and this value is greater than 10


4) None

Grade:12

1 Answers

Badiuddin askIITians.ismu Expert
148 Points
12 years ago

Dear Mayank

3 balls are selected without replacement if  no two of the selected balls have same colour then 

 = bC1 * 2bC1 *3bC

 

Probability P =[ bC1 * 2bC1 *3bC]/6bC3

                    =6b2 /(6b-1)(6b-2)

 for P = 0.3

  6b2 /(6b-1)(6b-2)  =0.3

  8b2 -9b +1 =0

  b=1 and b =1/8

 b can not be 1/8

 so only one value of b =1

option b is correct

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