21A

YOUR ANSWER: 373 watts.

Wrong. But do not despair; we will go over the problem with you.

The problem again was to solve for the input power of a 4-hp motor operating at 80

percent efficiency.

a. Use the correct formula: Efficiency = output x 100.

input

b. Substitute known values 80 = 4 x 746 (watts/hp x 100).

input

c. Multiply both sides by "input"; thus,

80 x input = 4 x 746 x 100 x input.

input

d. "Input" on right side cancels out, and we have

80 x input = 4 x 746 x 100.

e. Divide both sides by 80:

80 x input = 4 x 746 x 100; thus,

80

80

input = 4 x 746 x 100 =

watts.

80

Complete the problem, then continue on to frame 26A.

IT0348

1-22

Integrated Publishing, Inc. |