Answer:
Unit conversions are merely a way of changing the measuring device for a particular value. Each value
has units measured in terms of distance, area, volume, time, rate, etc. A unit change does not change
the value itself, so the unit conversion process involves multiplying by 1 only.
In order to complete unit conversions, a conversion factor must be used. In order to convert from yards
to feet, the ratio must be known. This ratio can be written in three different ways.
Conversion Factor Unit Fraction Number 1 Unit Fraction Number 2
1 yard = 3 feet
1
3 feet
1 yard
= 1
1 yard
3 feet
=
Many times a conversion list or conversion table will give you just a numeric conversion factor. It can
be written either as 1 yard = 3 feet, or as 0.3333 yard = 1 foot.
When doing unit conversions, the thought process is best described as: What units do I have now and
what units do I want to have? The idea is to write what you have as a fraction and multiply by unit
fractions until the units you want are obtained. Units will divide out just like numbers in this system.
Here are a few basic examples, followed by some more complicated ones.
Example 1 How many minutes are in 3 days?
What we are starting with is 3 days. The conversions used will move days into hours, then hours into
minutes. The conversion factors are 1 day = 24 hours, and 1 hours = 60 minutes. Remember from
above that there were two unit fractions. You must choose which one to use in this problem to
eliminate units. Since we are starting with days, we will want to eliminate days.
My unit conversions will be 1
1day
24 hours
= and 1
1hour
60 minutes
= .
Then
14 24 4 34
14 2 44444 4 3 44444 14 2 44444 4 3 44444
123
4320 minutes
1hour
60 minutes
1day
24 hours
1
3 days
1hour
60 minutes
1day
24 hours
1
3 days 3 days =
⋅
⋅
=
⋅
⋅
=
Starting Multiply by unit Eliminate common Final value
value conversions units
Therefore, 3 days = 4320 minutes.
Example 2 How many teaspoons are in a gallon? (probably need a conversion table here)
1 gallon = 4 quarts, 1 quart = 2 pints, 1 pint = 2 cups, 1 cup = 16 tbsp, 1 tbsp = 3 tsp
123
14 2 44444444 4 3 44444444
14243
768 tsp
1 tbsp
3 tsp
1cup
16 tbsp
1pint
2 cups
qt 1
2 pint
1gal
qt 4
1
1gal 1gallon =
=
Starting Multiply by unit conversions Final value
Value and eliminate common units
Therefore, 1 gallon = 768 teaspoons.
