Question

choosing area, perimeter, volume, or surface area
you know how to find the perimeter, area, volume, and surface area of various figures. but knowing which to solve for takes practice.
remember: perimeter is the distance around a flat figure. area is the space inside a flat figure. volume is the space inside a three - dimensional figure. surface area is the sum of the areas of the faces of a three - dimensional figure.
some area and volume formulas are given on the ged math formula sheet. you can see these formulas and others on pages 220 and 221 of the tool kit.
for each problem, select whether to solve for perimeter, area, volume, or surface area. then solve the problem. round to the nearest whole unit if necessary.

1. how many cubic feet does the moving truck shown in the ad hold?

735
solve for: perimeter
area
volume
surface area
solution:

1. a revolving sprinkler sprays a lawn for a dis of 18 feet. how much ground is covered by sprinkler as it makes 1 complete revolution?

1018
solve for: perimeter
area
volume
surface area
solution:

Explanation:

Step1: Identify the quantity to find for the moving - truck problem

The question asks for the number of cubic feet the moving truck holds. Cubic feet is a measure of volume, so we solve for volume. The moving truck is a rectangular - prism. The volume formula for a rectangular prism is $V = l\times w\times h$, where $l = 15$ ft, $w = 7$ ft, and $h = 7$ ft.
$V=15\times7\times7$

Step2: Calculate the volume

$V = 15\times49=735$ cubic feet.

Step3: Identify the quantity to find for the sprinkler problem

The sprinkler makes a circular pattern. We want to find the amount of ground covered, which is the area of the circle. The area formula for a circle is $A=\pi r^{2}$, where the radius $r = 18\div2=9$ ft (the diameter is 18 ft).
$A=\pi\times9^{2}$

Step4: Calculate the area

$A=\pi\times81\approx3.14\times81 = 254.34\approx254$ square feet.

Answer:

1. Solve for: volume

Solution: $V = 15\times7\times7=735$ cubic feet

1. Solve for: area

Solution: $A=\pi\times(18\div2)^{2}=\pi\times81\approx254$ square feet