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

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

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