Basic Mathematics for College Students

Define American units of length.

The American system of measurement uses the units ofinch, foot, yard,andmileto

measure length. These units are related in the following ways.

American Units of Length

1 foot (ft)12 inches (in.) 1 yard (yd)36 inches

1 yard3 feet 1 mile (mi)5,280 feet

The abbreviation for each unit is written within parentheses.

The Language of Mathematics According to some sources, the inch was

originally defined as the length from the tip of the thumb to the first knuckle.

In some languages the word for inchis similar to or the same as thumb.For

example, in Spanish,pulgadais inch and pulgaris thumb. In Swedish,tumis

inch andtummeis thumb. In Italian,polliceis both inch and thumb.

2

444 Chapter 5 Ratio, Proportion, and Measurement

Self Check 2

Find the width of the circle.

Now TryProblem 29

Solution

Since the tick marks between 0 and 1 on the

ruler create eight equal spaces, the ruler is

scaled in eighths of an inch. The paper clip is

1 38 inches long.

Self Check 1

Find the length of the jumbo

paper clip.

Now TryProblem 27

EXAMPLE (^2) Find the length of the nail shown below.
StrategyWe will place a ruler below the nail, with the left end of the ruler (which
could be thought of as 0) directly underneath the head of the nail.
WHYThen we can find the length of the nail by identifying where its pointed end
lines up on the tick marks printed in black on the ruler.
Solution
Since the tick marks between 0 and 1 on the ruler create sixteen equal spaces, the
ruler is scaled in sixteenths of an inch.
The nail is 2 167 inches long.
1 2 3
––^7
16 in.
––^7
16 in.
16 spaces
2
Inches
1 2
(^3) –
8 in.
(^3) –
8 in.
8 spaces
1
Inches