A retail store had sales of $45,650 in april and $55,215 in may. the store employes eight full time workers who work a 40 hr week. in april the store also had six part-time workers at 11 hours per week and in may the store had 8 part timers at 18 hours per week.

using sales dollars as the measure of output, what is the percentage change in productivity (dollars output per labor hour) from april to may