To find the length of the diagonal path in the rectangular park, we can use the Pythagorean theorem. The formula for the diagonal \( d \) in a rectangle with width \( w \) and length \( l \) is:
\[ d = \sqrt{w^2 + l^2} \]
In this case, the width \( w = 30 \) yards and the length \( l = 40 \) yards.
Now, substituting these values into the formula:
\[ d = \sqrt{30^2 + 40^2} \] \[ d = \sqrt{900 + 1600} \] \[ d = \sqrt{2500} \] \[ d = 50 \]
Thus, the length of the diagonal path is \( 50 \) yards.
Rounding to the nearest tenth, the answer remains:
\[ \text{Length of the path} = 50.0 \text{ yards} \]