CBSE Class 11-science Maths Fundamental Principle of Counting
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Kindly answer this.
- number of ways of selecting pair of black squares in chessboard such that they have exactly one common corner is equal to ______________
- In a class there are 27 boys and 15 girls. The teacher wants to select a boys and a girl for the monitor ship of the class. In how many ways can the teacher make this selection?
- A room has 5 doors. In how many ways can a man enter the room through one and come out through a different door?
- How many words (with or without meaning) of three distinct letters of the English alphabets are there?
- How many numbers are there between 100 and 1000 in which all the digits are distinct?
- How many three digit odd numbers can be formed by using the digits 1,2,3,4,5,6 If: 1) the repetition of digits is not allowed? 2) the repetition of digits is allowed?
- A mint prepares metallic calendars specifying months, dates and days in the form of monthly sheets (one plate for each month). How many types of February calendars should he prepare to serve for all the possibilities in the future years?
- In how many ways 5 rings of different types can be worn in 4 fingers?
- How many numbers are there between 100 and 1000 which have exactly one of their digits as 7?