Chapter 2 Measuring Length

2.1 Imperial units of measure Inch – A unit of length used in the imperial system. The symbol used to show inches is ,, ie. 1” would be one inch (12” = 1ft) Foot – The basic unit of length in the imperial system. The symbol used is ‘ ie. 4’ would be four feet (1’ = 12”) Yard – A unit of measure consisting of 3 ft (1yd = 3ft)

Adding imperial units When the units are the same we will just add them. ie. 4” + 11” = 15” Since imperial units can come in fractions we need to be able to deal with fractions. ie. 4 1/8” + 5 1/16” = ??? (lets review)

Steps to adding fractions Change both numbers into improper fractions. 4 1/8” + 5 1/16” = becomes… 33/8” + 81/16” = Now we need to get a common denominator

Common Denominator Multiply to get the bottom of the fractions to be the same. 33/8” + 81/16” = Both fractions can have 16 as their denominator. So, multiply the top and bottom of the first fraction by 2. 66/16” + 81/16” =

Add the numerators Add the top of the fractions and write them over the common denominator. 66/16” + 81/16” = 147/16 Now convert the improper fraction back to a mixed number. 147/16 = 9 3/16”

Example 1 Two kitchen cupboards are being build. The first is 13 ¾”. The second cupboard measures 17 ½”. What is the width of both cupboards when they are installed?

Example 2 An exhaust system needs to be repaired in two separate places. The first piece of pipe needs to be 17 5/16”. The second piece of pipe will need to be 9 ¼”. What is the total length of pipe?

You Try A phone charger is 34 ½” long. If the outlet adaptor is 2 1/8” long, what is the farthest it can reach?

Practice Worksheet on adding fractions with unlike denominators.