ALWAYS use significant figure rules. Remember that these rules apply to all numbers that are measurements. In working this problem, assume the value of "g" to be 9.8 m/s2 with two (2) significant digits unless otherwise stated.
A pulley system lifts a 500-lb block 1.0 foot with an effort of only 50 lb. If the 50 lb moves 30 feet, calculate the efficiency of the pulley system.

33 %
30. %
67 %
70. %