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Vijay wrote  4 different letter to send to 4 different addresses .for each letter, he prepared one envelope with its correct address. if the four letters are to be put into 4 envelopes at random in how many ways can we put the letters so that only two of the letter goes to the right envelope?

2

4

1

6
asked in Combinatory by Active (1.8k points)   | 16 views

1 Answer

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Best answer

For this, first we select two letters whose position is correct.. This can be done in 4C2 ways = 6 ways.. 

For the remaining two letters,  we need to do derangement which is done in D= 2!/2 = 1 way.. (the only way to derange two objects is to swap them).. 

Hence number of ways = 6 * 1 = 6.. Hence D)  should be correct option.. 

answered by Veteran (76.9k points)  
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