RATIO AND PROPORTION

RATIO AND PROPORTION
Another example:
How many milliliters of tetracycline
suspension, which contains 250
mg of tetracycline in each five
milliliters, must be administered to
give a patient 150 mg?
The proportion should be as follows:
250 mg = 150 mg
5 milliliters X milliliters
250 (X) = 5 (150)
250X = 750
X = 750
250
X = 3 ml
14
Example problem:
How many grams of potassium
permanganate (KMnO4) are needed to
make this prescription?
KMNO4 Q.S 120
DIST.WATER AND
MFD.1;5000 SOL.
SIG.US USD
Before calculation, the prescription must
be analyzed.
-the pharmacist should dispense a solution
of potassium permanganate in distilled
water.
-the solution should have a strength
equivalent to 1 gram per 5000 milliliters
- and the pharmacist should dispense 120
milliliters of the solution.
The expression of strength will be the
first ratio of the proportion:
1 gram = _______________
5000 ml
Assign the X value:
1 gram = X gram
5000 ml
Find the other known factor:
1 gram = X gram
5000 ml 120 ml
Then, cross-multiply:
5000 (x) = 1 (120)
5000 x = 120
Solve for X:
X = 120
5000
X = 0.024
Refer to the proportion for the units of X:
X = 0.024 gram #