CAT 2025 Lesson : Permutations & Combinations - Past Questions
11. Past Questions
Question 1
Sam has forgotten his friend’s seven-digit telephone number. He remembers the following: the first three digits are either 635 or 674, the number is odd, and the number nine appears once. If Sam were to use a trial and error process to reach his friend, what is the minimum number of trials he has to make before he can be certain to succeed? [CAT 2000]
10000
2430
3402
3006
Answer: (3) 3402
Question 2
In a sports meet for senior citizens organized by the Rotary Club in Kolkata, 9 married couples participated in Table Tennis mixed double event. The number of ways in which the mixed double team can be made, so that no husband and wife play in the same set, is [IIFT 2013]
1512
1240
960
640
Answer: (1) 1512
Question 3
In a locality, there are ten houses in a row. On a particular night a thief planned to steal from three houses of the locality. In how many ways can he plan such that no two of them are next to each other? [XAT 2013]
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