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The average of 13 results is 60. If the average of first 7 result is 59 and that of last 7 results is 61, What will be the seventh result?
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- 90
- 50
- 75
- 60
- None of the above
Correct Option: D
According to the fundamental to the fundamental formula
Average(A)= Sum (S) / Number(N)
From the question 60 = S / 13
∴ S = 60 x 13 = 780
Sum of first seven result = 59 x 7 = 413
Sum of last seven result = 61 x 7 = 427
∴ 7th result = (Sum of first seven result) + (Sum of last seven results) - (Sum of all the results)
= (413 + 427 - 780 )
= (840 - 780)
= 60
NoteSum of first seven when added to the sum of last seven result, then repetition of 7th result takes place.
