Explanation

Initially, the average of five numbers is 27, so the sum of these five numbers is:

5 x 27 = 135

If one number is excluded, the average becomes 25, which means the sum of the remaining four numbers is:

4 x 25 = 100

Now, let's find the excluded number by subtracting the sum of the remaining four numbers from the initial sum:

135 - 100 = 35

So, the excluded number is 35.