Q21 In how many ways can 6 people be seated at a round table?

Q22 8 directors, the vice chairman and the chairman are to be seated around a circular table. If the chairman should sit between a director and the vice chairman, in how many ways can they be seated?

Q23 Find the number of ways in which 4 stones, chosen from 7 different stones can be placed on a necklace .

Q24 A four digit number is formed using digits 1, 3, 5, and 7 without repeating any one of them. What is the sum of all such possible numbers?

Q25 In how many ways 8 ice creams can be selected from 15 identical ice creams?

Q26 In a group of 6 boys and 4 girls, four children are to be selected. In how many different ways can they be selected such that at least one boy should be there?

Q27 How many 3 digit number can be formed with the digits 5, 6, 2, 3, 7 and 9 which are divisible by 5 and none of its digit is repeated?

Q28 There are 4 bananas, 7 apples and 6 mangoes in a fruit basket. In how many ways can a person make a selection of fruits from the basket. (Assume all the fruits are similar)

Q29 There are 4 bananas, 7 apples and 6 mangoes in a fruit basket. In how many ways can a person make a selection of one or more fruits from the basket. (Assume all the fruits are non-similar)

Q30 There are 15 points in a plane out of which 6 are collinear. Find the number of lines that can be formed from 15 points.