A city has 12 gates. In how many ways can a person enter the city through one gate and come out through a different gate?
Since, there are 12 ways to enter into the city. After entering into the city, the man can come out through a different gate in 11 ways.
Hence, by the fundamental principle of counting.
Total number of ways is 12 × 11 = 132 ways.
If n is the number of ways in which an examiner can assign 30 marks to 8 questions, giving not less than 2 marks to any quation find n/40.
Find the number of rectangles that you can find on a chessboard.
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Ten persons, amongst whom are A, B and C, are to speak at a function. If n is the number of ways in which it can be done if A wants to speak before B, and B wants to speak before C find n/800.
Find the largest such that
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