The average of 13 results is 70. The average of first seven is 65 :

The average of 13 results is 70. The average of first seven is 65 and that of the last seven is 75, the seventh result is:

  1. 67
  2. 68
  3. 70
  4. 70.5
Anurag Mishra Professor Asked on 11th December 2015 in Maths.
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  • 1 Answer(s)

    Answer:  (3) 70 

    Explanation:-
    The average of 13 results = 70
    Then, the sum of 13 results = 70 x 13
     = 910

    The average of first seven results = 65
    Then, the sum of first seven results = 65 x 7
     = 455

    The average of last seven results = 75 x 7 
     = 525

    So, The seventh result = (455 + 525) – 910
     = 980 – 910
     = 70

    Then, the seventh result is 70. 

    Hence, the answer is (3) 70. 

    Anurag Mishra Professor Answered on 11th December 2015.
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