a. Example--If one aspirin tablet contains five grains of aspirin, then how
many tablets will you give in order for the patient to receive 15 grains of aspirin?
NOTE:
The EXPRESSION OF STRENGTH is "one tablet contains five grains of
aspirin" and should be written as the first ratio of the proportion.
IF
THEN
1 tablet =
___________
5 grains
b. Next, assign "X" its proper place in the second proportion. Because the
question asks "How many tablets?" the "X" is placed opposite the tablets in the first
ratio.
IF
THEN
1 tablet = X tablets
5 grains
c.
The question asks you to calculate the number of tablets required in
order to give 15 grains of aspirin; therefore, the 15 grains will be placed opposite the
grains in the first ratio.
IF
THEN
1 tablet = X tablets
5 grains
15 grains
NOTE:
Prior to cross-multiplying, be sure that corresponding units in each ratio are
the same.
2-6.
SOLVING for "X"
a. You have set up the proportion:
IF
THEN
1 tablet = X tablets
5 grains 15 grains
b. Now, cross multiply:
5(X) = 1(15)
MD0904
2-4