• Home
  • Textbooks
  • Essential Math and Calculations for Pharmacy Technicians
  • Using Ratios, Proportions, and Percentages in Dosage Calculations

Essential Math and Calculations for Pharmacy Technicians

Indra K. Reddy, Mansoor A. Khan

Chapter 3

Using Ratios, Proportions, and Percentages in Dosage Calculations - all with Video Answers

Educators


Chapter Questions

04:27

Problem 1

How many grams of salicylic acid and benzoic acid should be used in preparing 100 grams of an ointment containing $12 \%$ and $6 \%$ of each, respectively?

Carlene Jimenez
Carlene Jimenez
Numerade Educator
02:53

Problem 2

How many grams of boric acid should be used in compounding the following prescription:

Pronoy Sinha
Pronoy Sinha
Numerade Educator
01:52

Problem 3

What is the amount of potassium permanganate (in g) that should be used in compounding the following prescription?
$\mathrm{R}$
Potassium permanganate $0.03 \%$
Aqua ad $\quad 600 \mathrm{~mL}$

Lottie Adams
Lottie Adams
Numerade Educator
02:32

Problem 4

What is the percentage strength of boric acid if 50 grams are dissolved in $350 \mathrm{ml}$ of deionized distilled water?

Vishal Sharma
Vishal Sharma
Numerade Educator
04:01

Problem 5

In preparing $500 \mathrm{~mL}$ of a topical formulation, a community pharmacist used $8 \mathrm{~mL}$ of liquid phenol. What is the percentage strength $(\mathrm{v} / \mathrm{v})$ of the liquefied phenol in this topical formulation?

Ronald Prasad
Ronald Prasad
Numerade Educator
02:13

Problem 6

In preparation of $100 \mathrm{~mL}$ mouthwash, a pharmacist used $250 \mathrm{mg}$ of menthol. What is the percentage (w/v) of menthol in this mouthwash?

Ian Maurer
Ian Maurer
Numerade Educator
03:07

Problem 7

What is the amount of codeine sulfate to be used in compounding the following prescription?

HM
Hajiangelo Malinao
Numerade Educator
01:09

Problem 8

What is the amount of methyl salicylate in $(\mathrm{mL})$ that should be used in compounding the following prescription?
$\mathrm{R}$
Methyl salicylate & $6 \%$
Isopropanol & $150 \mathrm{~mL}$

Nicholas Mogoi
Nicholas Mogoi
Numerade Educator
01:54

Problem 9

What is the amount of peppermint oil (in $\mathrm{mL}$ ) that should be used in compounding aromatic water in the following prescription?
$\mathrm{R}_x$
Peppermint oil $2 \%$
Water to $220 \mathrm{~mL}$

Alison Rodriguez
Alison Rodriguez
Numerade Educator
01:04

Problem 10

How many grams of drug A should be dissolved in $140 \mathrm{~mL}$ of distilled water to prepare $8 \%(w / v)$ solution?

Jorge Villanueva
Jorge Villanueva
Numerade Educator
03:15

Problem 11

How many grams of a drug substance are needed to prepare $200 \mathrm{~mL}$ of a $10 \%(w / w)$ solution in water?

Luke P
Luke P
Numerade Educator
03:15

Problem 12

How many grams of a dorzolamide are needed to prepare $60 \mathrm{~mL}$ of a $2 \%$ (w/w) ophthalmic solution in isotonic solution?

Luke P
Luke P
Numerade Educator
01:57

Problem 13

Express each of the following concentrations as a ratio strength:
a. $2 \mathrm{~g}$ of active ingredient in $50 \mathrm{~mL}$ of the solution
b. $0.2 \mathrm{mg}$ of active ingredient in $2 \mathrm{~mL}$ of the solution
c. $25 \mathrm{mg}$ of active ingredient in $5 \mathrm{~mL}$ of the solution
d. $1 \mathrm{mg}$ of active ingredient in $1 \mathrm{~mL}$ of the solution

David Collins
David Collins
Numerade Educator
02:32

Problem 14

How many milligrams of a benzalkonium chloride should be used in preparing 5 liters of a $0.001 \%$ solution?

Angelina Chavez
Angelina Chavez
Numerade Educator
01:20

Problem 15

A liquid medication contains $2.5 \mathrm{mg}$ of fluoxetine hydrochloride per 75 milliliters. Express the milligram percent ( $\mathrm{mg} \%)$ concentration of this preparation.

Susan Hallstrom
Susan Hallstrom
Numerade Educator

Problem 16

An injection contains $50 \mathrm{mg}$ pentobarbital sodium in each $\mathrm{mL}$ of solution. What is the percentage strength $(w / v)$ of the solution?

Check back soon!
01:04

Problem 17

If $500 \mathrm{~g}$ of dextrose monohydrate are dissolved in enough water to make $20 \mathrm{~L}$, what is the percentage strength (w/v) of the solution?

Chareen Guzman
Chareen Guzman
Numerade Educator
View

Problem 18

How many milliliters of a $0.9 \%$ (w/v) of sodium chloride can be prepared from $11.25 \mathrm{~g}$ of sodium chloride?

Jean Gephart
Jean Gephart
Numerade Educator
01:02

Problem 19

If $50 \mathrm{~g}$ of magnesium citrate are dissolved in enough water to make $2.5 \mathrm{~L}$, what is the percentage strength $(w / v)$ of the solution?

Amy Jiang
Amy Jiang
Numerade Educator
01:43

Problem 20

What is the percentage strength (w/w) of a solution made by dissolving $250 \mathrm{~g}$ of potassium chloride in $750 \mathrm{~mL}$ of water?

Marissa Turner
Marissa Turner
Numerade Educator
01:23

Problem 21

If $100 \mathrm{mg}$ of docusate sodium are dissolved in water and the volume is made up to $10 \mathrm{~mL}$, what is the percentage strength (w/w) of the solution?

Lottie Adams
Lottie Adams
Numerade Educator
00:41

Problem 22

A formula for a mouth rinse contains $1 / 10 \%(w / v)$ of zinc chloride. How many grams of zinc chloride should be used in preparing 10 liters of the mouth rinse?

Nicole Smina
Nicole Smina
Numerade Educator
01:23

Problem 23

What is the percentage strength (w/w) of a solution made by dissolving $0.3 \mathrm{~g}$ of cimetidine hydrochloride in $90 \mathrm{~g}$ of water?

Lottie Adams
Lottie Adams
Numerade Educator
04:51

Problem 24

How many milliliters of resorcinol monoacetate liquid should be used to prepare a liter of a $15 \%(\mathrm{v} / \mathrm{v})$ lotion?

Debasish Das
Debasish Das
Numerade Educator
04:44

Problem 25

How many milligrams of sodium fluoride must be dissolved in $500 \mathrm{~mL}$ of water to make $0.05 \%(\mathrm{w} / \mathrm{w})$ solution?

Crystal Wang
Crystal Wang
Numerade Educator
02:08

Problem 26

If one liter of a solution contains $250 \mathrm{~g}$ of active drug, what is its percentage strength, expressed as $w / v$ ?

Bobby Barnes
Bobby Barnes
University of North Texas
02:02

Problem 27

How many grams of calcium carbonate should be used in preparing $100 \mathrm{~mL}$ of $10 \%$ calcium carbonate suspension?

Dr.  Satish  Ingale
Dr. Satish Ingale
Numerade Educator
00:57

Problem 28

If a patient is instructed to take $250 \mathrm{~mL}$ of $16 \% \mathrm{w} / \mathrm{v}$ of an oral solution, how many grams of the drug will he consume?

Thomas Harr
Thomas Harr
Numerade Educator
01:18

Problem 29

How many grams of iodine are represented in a $20 \mathrm{~mL}$ of $20 \%$ w/v iodine solution?

Will Li
Will Li
Numerade Educator
01:05

Problem 30

If $230 \mathrm{~mL}$ of a solution contains $46 \mathrm{mg}$ of drug, what is the strength of this solution in percent $(\mathrm{w} / \mathrm{v})$ ?

Chareen Guzman
Chareen Guzman
Numerade Educator
04:51

Problem 31

If $250 \mathrm{~mL}$ of a $0.1 \%$ solution is mixed with $150 \mathrm{~mL}$ of a $0.3 \%$ solution, what will be the strength (percent $w / v$ ) of the final solution?

Debasish Das
Debasish Das
Numerade Educator
View

Problem 32

What is the percent (w/v) strength of a solution that has $500 \mathrm{mg}$ of drug in $200 \mathrm{~mL}$ ?

Richelle Chappell
Richelle Chappell
Numerade Educator

Problem 33

What is the percentage strength (in $w / v$ ) of a $5 \mathrm{mg}$ in $5 \mathrm{~mL}$ solution?

Check back soon!
01:13

Problem 34

While preparing $250 \mathrm{~mL}$ of $2 \%(w / v)$ solution, a pharmacist mistakenly used only $4.5 \mathrm{~g}$ of drug. How many more milligrams of this drug are needed to get the correct strength?

Shalini Tyagi
Shalini Tyagi
Numerade Educator