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Home Aptitude Square Root and Cube Root See What Others Are Saying!
  • Question
  • If 3a=4b=6c and a+b+c=2729 , then a2+b2+c2 =?


  • Options
  • A. 81
  • B. 83
  • C. 87
  • D. None of these

  • Correct Answer
  • 87 

    Explanation

    4 b = 6 c ? b = 3 2 c         a n d       3 a = 4 b ? a = 4 3 b = 4 3 ( 3 2 c ) = 2 c  

    a + b + c = 27 29       ? 2 c + 3 2 c + c = 27 29     ? c = 6 29

     

      ? a 2 + b 2 + c 2 = ( a + b + b ) 2 - 2 ( a b + b c + c a )  

     

    = ( 27 29 ) 2 - 2 2 c × 3 2 c + 3 2 c × c + c × 2 c  

     

      = 729 × 29 - 2 × 13 2   c 2

    = 87


  • More questions

    • 1. 
      A man buys 3 cows and 18 goats in ? 47,200. Instead if he would have bought 8 cows and 3 goats, he had to pay ? 53,000 more. Cost of one cow is:

    • Options
    • A. ? 10,000
    • B. ? 11,000
    • C. ? 12,000
    • D. ? 13,000
    • Discuss
    • 2. Six years ago, the ratio of the ages of Kunal and Sagar was 6 : 5. Four years hence, the ratio of their ages will be 11 : 10. What is Sagar's age at present?

    • Options
    • A. 16 years
    • B. 18 years
    • C. 20 years
    • D. Cannot be determined
    • E. None of these
    • Discuss
    • 3. 
      (17.28 ÷? ) / (3.6 x 0.2) = 2

    • Options
    • A. 120
    • B. 1.20
    • C. 12
    • D. 0.12
    • Discuss
    • 4. 
      If a, b and c are non-zero, a + (1/b) = 1 and b + (1/c) = 1, then the value of abc is

    • Options
    • A. -3
    • B. 1
    • C. -1
    • D. 3
    • Discuss
    • 5. 
      A ladder 15 m long reaches a window which is 9 m above the ground on one side of street. Keeping its foot at the same point, the ladder is turned to the other side of the street to reach a window 12 m high. What is the width of the street:

    • Options
    • A. 31 m
    • B. 12 m
    • C. 30 m
    • D. 21 m
    • Discuss
    • 6. 
      4, 2, 3.5, 7.5, 26.25, 118.125

    • Options
    • A. 118.125
    • B. 26.25
    • C. 3.5
    • D. 2
    • Discuss
    • 7. 
      If the square of the sum of two numbers is equal to 4 times of their product. then the ratio of these numbers is:

    • Options
    • A. 2 : 1
    • B. 1 : 3
    • C. 1 : 1
    • D. 1 : 2
    • Discuss
    • 8. 
      What is the area of a square having perimeter 68 cm?

    • Options
    • A. 361 sq cm
    • B. 284 sq cm
    • C. 269 sq cm
    • D. 289 sq cm
    • Discuss
    • 9. A and B can do a job together in 7 days. A is 1¾ times as efficient as B. The same job can be done by A alone in :

    • Options
    • A.

      9 1 days
      3

    • B. 11 days
    • C.

      12 1 days
      4

    • D.

      16 1 days
      3

    • Discuss
    • 10. 
      Area of a square is 1/2 hectare. The diagonal of the square is?

    • Options
    • A. 250 meter
    • B. 100 meter
    • C. 50? 2 meter
    • D. 50 meter
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