A box contains two white, three black and four red balls. In how many ways
can three balls be drawn from the box, if atleast one black ball is to be included in the draw.

Find the number of integers greater than 7000 that can be formed with the digits 3, 5, 7, 8 and 9 where no digits are repeated.

If 20 lines are drawn in a plane such that no two of them are parallel and no three are concurrent, in how many points will they intersect each other?

In a certain city, all telephone numbers have six digits, the first two digits always being 41 or 42 or 46 or 62 or 64. How many telephone numbers have all six digits
distinct?

In an examination, a student has to answer 4 questions out of 5 questions; questions 1 and 2 are however compulsory. Determine the number of ways in which the
student can make the choice.

A convex polygon has 44 diagonals. Find the number of its sides

18 mice were placed in two experimental groups and one control group, with all groups equally large. In how many ways can the mice be placed into three groups?

A bag contains six white marbles and five red marbles. Find the number of ways in which four marbles can be drawn from the bag if (a) they can be of any colour (b) two must be white and two red and (c) they must all be of the same colour.

In how many ways can a football team of 11 players be selected from 16 players?
How many of them will
(i) include 2 particular players?
(ii) exclude 2 particular players?

A sports team of 11 students is to be constituted, choosing at least 5 from Class XI and atleast 5 from Class XII. If there are 20 students in each of these classes, in how many ways can the team be constituted?

A group consists of 4 girls and 7 boys. In how many ways can a team of 5
members be selected if the team has
(i) no girls
(ii) at least one boy and one girl
(iii) at least three girls.