Q1. Eight different letters of the alphabet are given. Words of 4 letters are to be formed using only the given letters. Find the number of different words that can be formed if
(a) repetition of letters is not allowed,
(b) repetition of letters is allowed,
(c) at least one letter is repeated.

Q2. 36. (a) How many 3-digit numbers are there?
(b) How many 3-digit numbers are there such that at least one of their digits is 7?

Q3. The results of 8 matches (Win, Lose or Draw) are to be predicted. Find the number of different forecasts that contain exactly 6 correct results.

Hello, I need help with part Q1(c), Q2(b) and Q3. Could you explain them please. The answer is 2416 for c and 252 for b and 112 for Q3. Thanks in advance.