Question:
The mean of 5 numbers is 18. If one number is excluded, their mean is 16. Find the excluded number.
Solution:
The mean of 5 numbers is 18
Then, the sum of 5 numbers = 5 × 18 = 90
If one number is excluded
Then, the mean of 4 numbers = 16
∴ sum of 4 numbers = 4 × 16 = 64
Excluded number = 90 – 64 = 26.