How many 3-letter words can be formed using a, b, c, d, e if (i) repetition of letters is not allowed? (ii) repetition of letters is allowed?

How many 3-letter words can be formed using a, b, c, d, e if (i) repet

1.	How many 3-letter words can be formed using a, b, c, d, e if (i) repetition of letters is not allowed? (ii) repetition of letters is allowed?
Answer» Correct Answer - (i) 60 (ii) 125<br>(i) Total number of 3-letter words is equal to the number of ways of filling 3 places. First place can be filled in 5 ways by any of the given five letters. Second place can be filled in 4 ways by any of the remaining 4 letters and the third place can be filled in 3 ways by any of the remaining 3 letters.<br> So, the required number of 3-letter words `=(5xx4xx3)=60.`<br> (ii) When repetition of letters is allowed, each place can be filled by any of the 5 letters in 5 ways.<br> `therefore " the required number of ways "=(5xx5xx5)=125.`