Answer:
The mean of the lengths is 0.35 tenths of millimeters
Explanation:
A distribution is called uniform if each outcome has the same probability of happening.
The uniform distributon has two bounds, a and b, and it's mean is given by:

The lengths are uniformly distributed with values at every tenth of a millimeter starting at 590.1, and continuing through 590.8.
This means that

So, the mean is:

The mean of the lengths is 0.35 tenths of millimeters