To find the mean of the numbers $65, 1.25, 21, 72, 15.6$, you follow these steps:

1. Sum the numbers: $65 + 1.25 + 21 + 72 + 15.6 = 175.85$

2. Count the numbers: There are 5 numbers.

3. Divide the sum by the count: $\text{Mean} = \frac{175.85}{5} = 35.17$

Thus, the mean is 35.17.

Would you like more details or have any questions? Here are some related questions:

1. How do you calculate the median of a set of numbers?
2. What is the mode of the given numbers?
3. How does the mean differ from the median?
4. Can you explain the concept of weighted averages?
5. How do outliers affect the mean?

Tip: Always check your calculations for accuracy!