The ornamental design for a motorized wheelbarrow, as shown and described.
FIG. 1 is a left side perspective view of a motorized wheelbarrow showing my new design;
FIG. 2 is a right front perspective view thereof;
FIG. 3 is a rear perspective view thereof; and,
FIG. 4 is a front perspective view thereof.
The broken line showings of wheels, an electric motor, a battery pack and associated wiring are for illustrative purposes only and form no part of the invention.