The arithmetic mean (average) of the first 10 natural numbers is:

5.5

Firstly, a natural number is an integer greater than 0. Natural numbers begin at 1 and increment to 10 for first 10 natural numbers.

Therefore, the first ten natural numbers are 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.

Mean = \(\frac{sum \; of \; observations}{number \; of \; observations}\)

Then the mean of 10 numbers = \(\frac{ 1+2+3+4+5+6+7+8+9+10 }{10}\) = 5.5