The first five odd natural numbers are $1, 3, 5, 7, 9$. We need to find the cubes of these numbers: $1^3 = 1$ $3^3 = 27$ $5^3 = 125$ $7^3 = 343$ $9^3 = 729$ Now, we find the sum of these cubes: Sum $= 1 + 27 + 125 + 343 + 729 = 1225$. The number of terms is $5$. The average is the sum divided by the number of terms: Average $= \frac{1225}{5} = 245$. Therefore, the average of the cubes of the first five odd natural numbers is $245$.