Question:
The mean of five numbers is 27. If one number is excluded, their mean is 25. Find the excluded number.
Solution:
The mean of five numbers is 27
The sum of five numbers = 5 × 27 = 135
If one number is excluded, the new mean is 25
∴ Sum of 4 numbers = 4 × 25 = 100
∴ Excluded number = 135 – 100 = 35