1-6.
RATIOS
a. A ratio is the relation between like numbers or values, or a way to express a
fractional part of a whole. Ratios may be written:
As a fraction: _2_
3
As a division: 2 3
With the ratio or colon sign: 2:3
Using "per": 50 miles per hour (50mi/hr)
b. The strength or concentration of various drugs can be expressed as a ratio.
First, read the label of the drug and find the strength or concentration. Express this
strength as a ratio in fractional form, as in the following examples.
(1) Tolnaftate solution, 10 mg per ml = 10 mg
1 ml
(2) Guinine injection, 0.3 gm per ml = 0.3 gm
1 ml
(3) Kanamycin injection, 1.0 gm/3 ml = 1.0 gm
3 ml
(4) Isoproterenol inhalation, 1:200 = __1
200
(5) Epinephrine injection, 1:1000 = __1
1000
(6) Phenoxymethyl penicillin tablets 200,000 units = 200,000 units_
1 tablet
Sulfisoxazole tablets, 0.5 gm = 0.5 gm
1 tablet
1-7.
A proportion consists of two equal ratios and is essentially a statement of equality
between two ratios. For example:
2 = 4
5
10
MD0913
1-8