The average of the cubes of first nine natural numbers is:

Sum of cube of n natural numbers = n² × \(\frac{(n + 1)(n + 1)}{4}\)

Here n = 9

Sum of cube of 9 natural numbers = 9² × \(\frac{(9 + 1)(9 + 1)}{4}\) = 2025

Now, the average of cube of first 9 natural numbers= \(\frac{2025}{9}\) = 225