Question

the average of 15 results in a calculation is 40. the average of the first 7 results is 20 and of the last 7 result is 50. what is the value of the value of the eighth result

Answer 1

Solution:-
The average of 15 results in a calculation = 40
Then, the sum total of 15 results = 40 × 15 = 600
The average of first 7 results = 20
Then, the sum total of first 7 results = 20 × 7 = 140
The average of last 7 results = 50
Then, the sum total of last 7 results = 50 × 7 = 350
Therefore, 
The value of 8th result = 600 - (140 + 350)
= 600 - 490
The value of 8th result = 110
Answer.