c. Let's apply these principles in performing some conversions from other
systems to the metric system.
(1) Weight. Express 5 grains as milligrams.
(a) Step 1. Write the conversion factor as your IF ratio:
IF
1 gr
60 mg
(b) Step 2. Write the unknown factor as your THEN ratio:
THEN
5 gr
X mg
(c) Step 3. Solve for the unknown as in any other ratio and proportion
problem.
IF
1gr
= THEN
5 gr
60 mg
X mg
1X
5 60
=
X = 300 mg (answer)
(2) Volume. Express 4 fluid ounces as milliliters.
(a) Step 1. Write the conversion factor as your IF ratio:
IF
1 fl oz
30 ml
(b) Step 2. Write the unknown factor as your THEN ratio:
THEN
4 fl oz
X ml
(c) Step 3. Solve for the unknown.
IF
1 fl oz
THEN
4 fl oz
30 ml
=
X ml
1 X
4 30
=
X = 120 ml (answer)
MD0913
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