FIG. 1 is a front elevational view of a rear bumper for an automobile in accordance with an embodiment of our new design;
  
    FIG. 2 is a rear elevational view thereof;
  
    FIG. 3 is a top plan view thereof;
  
    FIG. 4 is a bottom plan view thereof;
  
    FIG. 5 is a left side elevational view thereof;
  
    FIG. 6 is a right side elevational view thereof;
  
    FIG. 7 is a right-side perspective view thereof; and,
  
    FIG. 8 is a left-side perspective view thereof.
  The ghosted or low contrasted showing is provided for the purposes of illustrating portions of the rear bumper for automobile that form no part of the claimed design. The broken line indicates the boundary of the claimed design and forms no part of the claimed design.