USING RATIOS TO CONVERT

QUICK!!! Quick! Tell me how many seconds are in

a year!!!!

CONVERTING The best way to understand the

rules for converting is to see them in action.  

Let's start with an example problem and go through the rules as we solve the problem.  

You will want to have a pencil, a calculator, and a piece of paper ready to go. 

EXAMPLE A roll of Christmas wrapping paper

contains 2.5 meters of paper. What is the length of the paper in yards?

Step 1: Write down the known values and the unknown values.

Step 2: Find the conversion factor that gives a ratio between meters and yards. 

Step 3:   Write the conversion factor as a fraction with the unit you want to convert to on top and set the problem up as an equation.

2.5 meters x  1.09yards =                            1 meter

2.725 yards

You can see that the unit meters will cancel.

EXAMPLE #2 Convert 325 millimeters to meters.

Step 1: Write down the known values and the unknown values.

Find the conversion factor that gives a ratio between meters and millimeters.  

1 meter = 1000 mm

Step 3: Write the conversion factor as a fraction with the unit you want to convert to on top and set the problem up as an equation.

325mm = 1 meter =                 1000 mm

.325 meters

The unit millimeters will cancel.

EXAMPLE #3 How many centuries are in 237,439

days?

Step 1: 

Step 2:

Step #3

Equation:

237,439 days x 1year  x  1century =     365 days 100 years

237,439   =   36500

                                  6.51 centuries The units days andyears will cancel.

REMEMBER Always remember to put the unit that

you want to convert to on top!

All conversion factors must be labeled! (meter, liter, year, etc .)

PRACTICE

How many seconds are in 768 days?

A car has traveled 7.2 miles.  How many inches did the car travel?