The average of 15 results is 21. The average of the first 7 of those is 21 and the average of the last 7 is 20. What is the 8th result?
Show answer & explanation
Correct answer: C
Explanation
The correct answeer is option 3 i.e. 28
According to the question
8th result = 15 * 21 - (7 * 21 + 7 * 20)
= 315 - 287
= 28