Math Word Problems Demystified - A Self Teaching Guide

Given any of the three variables, you can set up an equation and solve for
the fourth one. Unless otherwise specified, assume the fulcrum is in the center
of the lever.

EXAMPLE:Bill weighs 120 pounds and sits on a seesaw 3 feet from the
fulcrum. Where must Mary, who weighs 96 pounds, sit to balance it?

SOLUTION:

GOAL: You are being asked to find the distance from the fulcrum Mary
needs to sit to balance the seesaw.

STRATEGY: Use the formulaWL¼wlwhereW¼120,L¼3,w¼96,l¼x.

WL¼wl

120 ð 3 Þ¼ 96 ðxÞ

See Figure 16-2.

IMPLEMENTATION: Solve the equation:

120 ð 3 Þ¼ 96 ðxÞ

360 ¼ 96 x

Fig. 16-1.

Fig. 16-2.

LESSON 16 Solving Lever Problems 173