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  • Question
  • After replacing an old member by a new member, it was found that the average age of five members of a club is the same as it was 3 years ago. What is the difference between the ages of the replaced and the new member ?


  • Options
  • A. 12
  • B. 13
  • C. 14
  • D. 15

  • Correct Answer
  • 15 

    Explanation

    i) Let the ages of the five members at present be a, b, c, d & e years. 

    And the age of the new member be f years. 

    ii) So the new average of five members' age = (a + b + c + d + f)/5 ------- (1) 

    iii) Their corresponding ages 3 years ago = (a-3), (b-3), (c-3), (d-3) & (e-3) years 

    So their average age 3 years ago = (a + b + c + d + e - 15)/5 = x ----- (2) 

    ==> a + b + c + d + e = 5x + 15 

    ==> a + b + c + d = 5x + 15 - e ------ (3) 

    iv) Substituting this value of a + b + c + d = 5x + 15 - e in (1) above, 

    The new average is: (5x + 15 - e + f)/5 

    Equating this to the average age of x years, 3 yrs, ago as in (2) above, 

    (5x + 15 - e + f)/5 = x 

    ==> (5x + 15 - e + f) = 5x 

    Solving e - f = 15 years. 

    Thus the difference of ages between replaced and new member = 15 years.


  • More questions

    • 1. The milk and water in two vessels are in the ratio of 3 : 1 and 7 : 11 respectively. In what ratio should the liquid in both the vessels be mixed to obtaina new mixture containing half milk and half water?

    • Options
    • A. 5 : 7
    • B. 4 : 9
    • C. 1 : 1
    • D. 4 : 7
    • Discuss
    • 2. In a mixture of 35 litres, the ratio of milk and water is 4:1. If 7 litres of water is added to the mixture, the ratio of milk and water of the new mixture will be

    • Options
    • A. 2:1
    • B. 1:2
    • C. 4:5
    • D. 5:4
    • Discuss
    • 3. 
      If the three- fourth of number is subtracted from the number, the value so obtained is 163. What is that number?

    • Options
    • A. 625
    • B. 562
    • C. 632
    • D. 652
    • Discuss
    • 4. 8 litres are drawn from a flask containing milk and then filledwith water. The operation is performed 3 more times. Theratio of the quantity of milk left and total solution is 81/625.How much milk the flask initially holds?

    • Options
    • A. 10 ltr
    • B. 20 ltr
    • C. 30 ltr
    • D. 40 ltr
    • Discuss
    • 5. The square root of 64009 is:

    • Options
    • A. 253
    • B. 347
    • C. 363
    • D. 803
    • Discuss
    • 6. 4, -8, 16, -32, 64, (....)

    • Options
    • A. 128
    • B. -128
    • C. 192
    • D. -192
    • Discuss
    • 7. 
      6.39 x 128.948 + 5.215 ÷ 12.189 + 25.056 =?

    • Options
    • A. 800
    • B. 900
    • C. 850
    • D. 950
    • Discuss
    • 8. 
      A 240 m long train crosses a platform of equal length in 27 s. What is the speed of the train in km/h?

    • Options
    • A. 48
    • B. 60
    • C. 56
    • D. 64
    • Discuss
    • 9. 
      If 1 / 3.718 = .2689, then the value of 1 / .0003718 is?

    • Options
    • A. 2689
    • B. 2.689
    • C. 26890
    • D. .2689
    • Discuss
    • 10. 
      A can do a piece of work in 24 days. If B is 60% more efficient than A, then the number of days required by B to do the same piece of work is?

    • Options
    • A. 10
    • B. 15
    • C. 12
    • D. 9.6
    • Discuss


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