1.3 Warm-Up
1. Fill in the blanks.
a) 48 inches = ______ feet
b)______ yards = 15 feet
c) 1 mile = ______ yards
2. Fill in the blanks.
a) 1500 cm = ______ m
b) ______ m = 380 cm
c) 50 cm = ______ mm
3. Estimate each of the following measurements.
a) your height in centimetres
b) the length of your thumb in inches
c) the length of your foot in centimetres
5
8
4. Show how you would multiply 1 and 2.1 without a calculator.
5. A walkway has a length of 3.5 m and a width of 1.2 m. A decorative planted edge that is
10 cm wide is placed along the longer sides of the walkway.
a) What is the total width of the walkway and the decorative edge?
b) What is the length of the walkway?
Foundations & Pre-Calculus 10
1.3 Converting Between SI and Imperial Systems
There are both exact and approximate conversion factors that are used to change
SI units into Imperial units and vice versa.
For example, it is defined that one yard is equal to 0.9144 m. This is an exact
conversion factor. Using this factor, we can determine how long a foot is in metres.
1 yd  0.9144m
3 ft  0.9144m
3 ft 0.9144m

3
3
1 ft  0.3048m
Remember: 1 yd = 3 ft
Here we are simply isolating 1 ft on one side of the equals sign.
1 ft = 0.3048 is another EXACT conversion factor.
Now, let’s see if 1 m is equal to an exact number of yards. Begin with the same
equivalency statement as above.
0.9144m  1 yd
0.9144m
1yd

0.9144
0.9144
1m  1.0936... yd
Remember that 0.9144m divided by 0.9144 is equal to ONE metre and
NOT ZERO!
This is an APPROXIMATE conversion factor.
The following are some commonly used equivalencies between SI and Imperial
Systems.
EXACT
1 in. = 2.54 cm
1 ft = 30.48 cm
1 yd = 0.9144 m
APPROXIMATE
1 mm  0.0394 in.
1 m  3.281 ft
1 cm  0.3937 in.
1 km  0.6214 mi
1 m  1.094 yd
1 mi  1.609 km
Use the approximate conversions for estimates and the exact conversions for
precise calculations.
Examples:
1) Convert each of the following lengths into the given units.
a) 5 cm = __________ in.
b) 4 m = _____________yd
c) 6 ft = ___________ m
d) 0.5 yd = ____________ cm
2) You are looking to tile a kitchen with rectangular tiles. The kitchen measures 30’
by 20’ and the tiles are 45 cm by 30 cm.
a) Find the area of the kitchen and the area of each tile in the same units.
b) If you ignore the layout of the tiles, how many whole tiles would be necessary to
tile the kitchen?
c) You want to run the tiles lengthwise throughout the kitchen (i.e. the long side of
the tile will be parallel to the longer walls of the kitchen). Keeping in mind this
layout, how many whole tiles would be needed?