There are two urns. Urn A has 3 distinct red balls and urn B has 9 distinct blue balls. From each urn two balls are taken out at random and then transferred to the other. The number of ways in which this can be done is

  • Option 1)

    3

  • Option 2)

    36

  • Option 3)

    66

  • Option 4)

    108

 

Answers (1)

As we learnt in

Theorem of Combination -

Each of the different groups or selection which can be made by taking r things from n things is called a combination.

^{n}c_{r}=\frac{(n)!}{r!(n-r)!}

- wherein

Where 1\leq r\leq n

 

 Urn A \rightarrow 3 Red balls.

Urn B \rightarrow 9 Blue balls

Number of ways =^{3}C_{2}\times^{9}C_{2}=\frac{3\times 9\times 8}{2}=108

Correct option is 4.

 


Option 1)

3

This is an incorrect option.

Option 2)

36

This is an incorrect option.

Option 3)

66

This is an incorrect option.

Option 4)

108

This is the correct option.

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