Question

Ten different letters of an alphabet are given. Words with five letters are formed from these given letters. Determine the number of words which have at least one letter repeated.

Options

• 69762

• 69676

• 69760

• 69766

Answer 1

69760

Explanation:

Number of all letter words is = 10⁵

All five letter words which have no letter repeated is = ¹⁰P₅ = 30240

Number of words which have at least one letter repeated is = 100000 – 30240 = 69760