Questions
Aiay writes letters to his five friends and addresses the corresponding. The number of ways can the letters be placed in the
envelops so that atleast two of them are in the wrong envelopes are
detailed solution
Correct option is C
Required number of ways =∑r=25 5C5−rD(r)=∑r=25 5!r!(5−r)!⋅r!1−11!+12!−13!+…+(−1)rr!=∑r=25 5!(5−r)!12!−13!+…+(−1)rr!=5!3!12!+5!2!12!−13!+5!1!12!−13!+14!+5!0!12!−13!+14!−15! =10+20+(60−20+5)+(60−20+5−1)=10+20+45+44=119Similar Questions
Suman writes letters to his five friends. The number of ways can be letters be placed in the envelopes so that atleast two of them are in the wrong envelopes are
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