The sum of 5 positive integers is 16. If we subtract the greatest integer from the sum, the average of remaining 4 integers would be 2.5. In the similar manner if we subtract the least one, the average of remaining 4 integers would be 3.75. The average of middle 3 integers will be
2.5 * 4 = 10 so the greatest number is 16 -10 = 6
3.75 * 4 = 15 so the least number is 16 - 15 = 1
thus the sum of middle 3 numbers = 16 - 6 - 1 = 9
average = 9/3 = 3