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  • Question

  • The ratio of two numbers is 4:7. If each of those numbers increased by 30, their ratio will become 5:8 . What is the average of these two numbers?


  • Options
  • A. 135
  • B. 145
  • C. 155
  • D. 165

  • Correct Answer
  • 165 

    Explanation

    Let the numbers be x and y.
    According to question,
    The ratio of two numbers is 4:7.
    ? x/y = 4/7
    ? 7x = 4y
    ? 7x - 4y = 0 ........................(1)
    Again According to question,
    If each of those numbers increased by 30, their ratio will become 5:8
    (x + 30) / (y + 30) = 5/8
    ? 8(x + 30) = 5(y + 30)
    ? 8x + 240 = 5y + 150
    ? 8x - 5y = -90 ..........................(2)
    Multiply 5 with equation (1) , we will get.
    35x - 20y = 0 ..................(3)
    Multiply 4 with equation (2), we will get.
    32x - 20y = -360 ............(4)
    Subtracts the Equation (4) from Equation (3). we will get,
    35x - 20y - (32x - 20y) = 0 - (-360)
    ? 35x - 20y - 32x + 20y = 360
    ? 3x = 360
    ? x = 120
    Put the value of x in equation (1) to get the value of y.
    7x - 4y = 0
    ? 7(120) - 4y = 0
    ? 840 - 4y = 0
    ? 4y = 840
    ? y = 210
    ? Average of the numbers = (x + y)/2
    put the vale of x and y.
    ? Average of the numbers = (120 + 210)/2
    ? Average of the numbers = 330/2
    ? Average of the numbers = 165

    • More questions

    • 1. 
      The value of (0.96)3 - (0.1)3 is:
      (0.96)2 + 0.096 + (0.1)2

    • Options
    • A. 0.86
    • B. 0.95
    • C. 0.97
    • D. 1.06
      • Discuss
    • 2. 
      A man has given one-fourth part of his property to his daughter, half part to his sons and one-fifth part given as charity. How much part of his property he has given?

    • Options
    • A. 1/20
    • B. 19/20
    • C. 1/10
    • D. 9/10
      • Discuss
    • 3. 
      When a 192 meters long rod is cut down into small pieces of length 3·2 meters each. Then how many pieces are available?

    • Options
    • A. 52
    • B. 68
    • C. 62
    • D. None of these
      • Discuss
    • 4. 
      If a * b = a + b + a/b, Then the value of 12 * 4 is

    • Options
    • A. 48
    • B. 19
    • C. 20
    • D. 21
      • Discuss
    • 5. 
      When A alone does a piece of work, he takes 25 days more than the time taken by (A + B) to complete that particular work, while B alone takes 49 days more than the time taken by (A + B) to finish the same work . A and B together will take what time for finish this work?

    • Options
    • A. 35 days
    • B. 25 days
    • C. 15 days
    • D. 45 days
      • Discuss
    • 6. 
      If the rate of interest rises from 6 1/2 to 8% a man's annual income increases by Rs. 4050. Find the capital.

    • Options
    • A. Rs . 270000
    • B. Rs . 370000
    • C. Rs . 300000
    • D. None of these
      • Discuss
    • 7. 16, 33, 65, 131, 261, (....)

    • Options
    • A. 523
    • B. 521
    • C. 613
    • D. 721
      • Discuss
    • 8. 
      16.7 + 12.38 -? =10.09

    • Options
    • A. 17.89
    • B. 18.99
    • C. 16.98
    • D. 20.09
      • Discuss
    • 9. 
      A mixture of 20 kg of spirit and water contains 10 % water. How much water must be added to this mixture to raise the percentage of water to 25 %?

    • Options
    • A. 4 kg
    • B. 5 kg
    • C. 8 kg
    • D. 30 kg
      • Discuss
    • 10. 
      A contractor undertakes to do a piece of work in 40 days. He engages 100 men at the begining and 100 more after 35 days and completes the work in stipulated time.
      If he had not engaged the additional men, how many days behind schedule would it be finished?

    • Options
    • A. 7
    • B. 18
    • C. 12
    • D. None
      • Discuss

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