The average of 9 results is 49. The average of the first 5 results is 55 and the average of the last 5 results is 43. What is the 5th result?

💡 Solution & Explanation

The first 5 and the last 5 results together make 10 results, but there are only 9: the 5th result is counted in both groups. Sum of the first 5 = 5 × 55 = 275; sum of the last 5 = 5 × 43 = 215; sum of all 9 = 9 × 49 = 441. So the 5th result = 275 + 215 − 441 = 49.