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Earn 100

A telegraph has five arms and each arm is capable of three distinct positions, including the position of rest. What is the total number of signals that can be made?

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Important Questions on Permutation and Combination

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Five different digits 7, 3, 6, 2, 5 are given. Out of these digits, 4-digits numbers are formed. Find the no. of 4-digit numbers formed, which have at least one digit repeated:
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Find the number of ways in which five gentlemen and three ladies can be seated in a row so that no two ladies are together:
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In how many ways can three prizes be distributed among four boys when no boy gets all the prizes?
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In a city M, the license plates consist of 3 letters consisting of consonants only. Any two license plates will be the same only if consists of the same 3 letters in the same order. How many license plates are possible if the letter M cannot occur as the last character and can occur only when the letter is immediately after it is T?
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A person has 12 notes of Rs 50 each, 9 notes of Rs 20 each, 5 notes of Rs 10 each and 4 notes of Rs 5 each. In how many different ways can be contribute to a Puja committee?
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There are four teams in each of the four groups A, B, C, and D. Every team in each group will play with each other once. The top teams from each will go to the next round and so on the top 2 teams will play final. The minimum number of matches played will be:
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In how many ways can the letters of the English alphabet be arranged so that there are eight letters between Y and Z, and no letters is repeated?
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A staircase contains 12 steps, can climb it 1 or 2 steps. But 8th step contains a big break so one cannot step on it. In how many ways can one reach the top?