The average of 13 results is 60. If the average of the first seven results is 59 and that of the last seven is 62 , the 7th no. is :
Answer & explanation
Correct answer: option 4
Average of 13 results = 60
⇒ Sum of these 13 results = 780
Sum of first seven numbers = 59 × 7 = 413
Sum of last seven numbers = 62 × 7 = 434
∴ 7th number = Sum of first seven numbers + Sum of last seven numbers − Sum of all numbers
7th number = 413 + 434 – 780 = 67