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  • Question
  • 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!

  • Correct Answer
  • 60 

    Explanation

    The digit in the unit's place should be greater than that in the tens' place.
    Hence, if digit 5 occupies the unit place, then remaining four digits need not to follow any order,hence required number = 4!
    However, if digit 4 occupies the unit place then 5 cannot occupy the ten;s position. Hence, digit at the ten's place and it will be filled by the digit 1, 2 or 3. This can happen in 3 ways. The remaining 3 digit can be filled in the remaining three place in 3! ways.
    Hence, in all, we have (3 x 3!) numbers ending in 4. Similarly, if we have 3 in the unit's place and it will be either 1 or 2. this can happen in 2 ways. Hence, we will have (2 x 3! ) number ending in 3 . Similarly, we can find that there will be 3! numbers ending in 2 and no number with 1. Hence, total number of numbers
    = 4! + (3) x 3! + (2 x 3!) + 3!
    = 4! + 6 x 3! = 24 + (6 x 6) = 60


  • More questions

    • 1. 
      If the price of 23 toys is Rs. 276, then what will the price (Rs.) of 12 toys?

    • Options
    • A. 144
    • B. 158
    • C. 159
    • D. 166
    • Discuss
    • 2. 
      .02 =(......?.....)%

    • Options
    • A. 20
    • B. 2
    • C. .02
    • D. .2
    • Discuss
    • 3. 
      If 36 men can do a piece of work in 25 hours, in how many hours will 15 men do it?

    • Options
    • A. 45
    • B. 55
    • C. 60
    • D. 72
    • Discuss
    • 4. 
      2?63 / 11 =233

    • Options
    • A. 4
    • B. 3
    • C. 6
    • D. 5
    • Discuss
    • 5. 
      When 121012 is divided by 12, the remainder is

    • Options
    • A. 0
    • B. 2
    • C. 3
    • D. 4
    • Discuss
    • 6. 
      Aarti can do a piece of work in 6 days. In how many days will she complete three time of work of same type?

    • Options
    • A. 18 days
    • B. 21 days
    • C. 3 days
    • D. 6 days
    • Discuss
    • 7. 
      750.0003 ÷ 19.999 =?

    • Options
    • A. 49
    • B. 18
    • C. 22
    • D. 38
    • Discuss
    • 8. 
      105, 85, 60, 30, 0, - 45, - 90?

    • Options
    • A. 0
    • B. 85
    • C. -45
    • D. 60
    • Discuss
    • 9. 
      Let A = {1, 2, {3, 4}, 5}. Which of the following statements is true?

    • Options
    • A. {3, 4} ? A
    • B. {3, 4} ? A
    • C. 1 ? A
    • D. {1, 2, 5} ? A
    • Discuss
    • 10. 
      Two vessels A and B contains milk and water mixed in the ratio 5 : 3 and 2 : 3. When these mixtures are mixed to form a new mixture containing half milk and half water, they must be taken in the ratio ?

    • Options
    • A. 2 : 5
    • B. 3 : 5
    • C. 4 : 5
    • D. 7 : 3
    • Discuss


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