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  • Question
  • There are 10 stations on a railway line. The number of different journey tickets that are required by the authorities, is


  • Options
  • A. 92
  • B. 90
  • C. 91
  • D. 93

  • Correct Answer
  • 90 

    Explanation

    There are 10 station on railway line.
    So, the number of different journey tickets between two station from given 10 stations from one side = 10C2 = 10 x 9/2 = 45.

    Similarly, number of different journey tickets from other side = 45
    ? Total number of tickets to be generated by authorities. = 45 + 45 = 90


  • Permutation and Combination problems


    Search Results


    • 1. 
      A question paper consists of two sections having respectively 3 and 5 questions. The following note is given on the paper. "It is not necessary to attempt all the question". One question from each section is compulsory. In how many ways, a candidate can select the question?

    • Options
    • A. 38
    • B. 217
    • C. 256
    • D. 320
    • Discuss
    • 2. 
      There are 14 points in a plane, out of which 4 are collinear. Find the number of triangles made by these points .

    • Options
    • A. 364
    • B. 360
    • C. 368
    • D. 365
    • Discuss
    • 3. 
      In how many ways, can 24 persons be seated around a circular table if there are is 13 seats?

    • Options
    • A. 24! / [13 x 11! ]
    • B. 22! / [14 x 12!]
    • C. 23! / [13 x 11!]
    • D. 24! / [12 x 12!]
    • Discuss
    • 4. 
      There is a 7-digit telephone number with all different digits. If the digit at extreme right and extreme left are 5 and 6 respectively, find how many such telephone number are possible?

    • Options
    • A. 120
    • B. 100000
    • C. 6720
    • D. 30240
    • Discuss
    • 5. 
      A mixed doubles tennis game is to be played between two teams ( each team consists of one male and one female). There are four married couples. No team is to consist of a husband and his wife. What is the maximum number of games that can be played?

    • Options
    • A. 12
    • B. 48
    • C. 36
    • D. 42
    • Discuss
    • 6. 
      The number of ways in which a committee of 3 ladies and 4 gentlemen can be appointed from a group consisting of 8 ladies and 7 gentlemen, if Mrs. X refuses to serve in a committee if Mr. Y is its member, is

    • Options
    • A. 1960
    • B. 3240
    • C. 1540
    • D. None of these
    • Discuss
    • 7. 
      A five-digit number divisible by 3 is to be formed using digits 0, 1, 2, 3, 4 and 5 without repetition, the total number of ways this can be done, is

    • Options
    • A. 122
    • B. 210
    • C. 216
    • D. 217
    • Discuss
    • 8. 
      A new flag is to be designed with six vertical stripes using some or all of the colour yellow, green,blue and red. Then, the number of ways this can be made such that no two adjacent stripes have the same colour is

    • Options
    • A. 12 x 81
    • B. 16 x 192
    • C. 20 x 125
    • D. 24 x 216
    • Discuss
    • 9. 
      An intelligence agency forms a code of two distinct digits selected from 0, 1, 2,....., 9 such that the first-digit of code is non-zero. The code, handwritten on a slip, can however potentially create confusion when read upside down, for examples the code 91 may appear as 16. how many codes are there for which no such confusion can arise?

    • Options
    • A. 80
    • B. 78
    • C. 71
    • D. 69
    • Discuss
    • 10. 
      How many numbers can be formed from 1, 2, 3, 4, 5, ( without repetition), when the digit at the unit's place must be greater than that in the ten's place?

    • Options
    • A. 54
    • B. 60
    • C. 51/3
    • D. 2 x 4!
    • Discuss


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