Pre-Algebra Demystified

Table 10.1 Conversion Factors for Length

1 mile (mi)¼1760 yards (yd)

1 yard (yd)¼3 feet (ft)

1 foot (ft) ¼12 inches (in.)

EXAMPLE

Change 5 yards to feet.

SOLUTION

Since we are going from large to small, and the conversion factor is 1 yd¼

3 ft, we multiply by 3 ft:

5yd3ft¼15 ft

EXAMPLE

Change 648 inches to feet.

SOLUTION

Since we are going from small to large, and the conversion factor is 1 ft¼

12 in., we divide:

648 in:12 in:¼54 ft:

Sometimes it is necessary to use an operation more than once to arrive at the

solution.

EXAMPLE

Change 79,200 feet to miles.

SOLUTION

Since no conversion factor for changing feet to miles is given in Table 10.1, it

is necessary to convert feet to yards and then convert yards to miles:

79,200 ft3ft¼26,400 yd

26,400 yd1760 yd¼15 miles

Math Note: If you know the conversion factor 1 mile¼5280 feet,

it is only necessary to divide once:

79,200 ft5280 ft¼15 mi

Another type of conversion has mixed units.

190 CHAPTER 10 Measurement