Ratio & Proportion PowerPoint Presentation
- 2. Ratio and Proportion: Objectives After reviewing this chapter, you should be able to 1. Define ratio and proportion. 2. Define means and extremes. 3. Set up a ratio and proportion in linear and fraction format. 4. Calculate problems for a missing term (x) using ratio and proportion. Copyright © 2022 by Elsevier Inc. All rights reserved.
- 3. Ratio and Proportion: Background A ratio indicates the division of two quantities Can be used to calculate all types of med problems or nurse/client ratios Example: 4 nurses to 28 clients = 1:7 ratio Some meds use ratio to express strength of solution Example: Epinephrine 1:1,000 Ratios should be expressed in lowest terms Copyright © 2022 by Elsevier Inc. All rights reserved.
- 4. Ratios Used to indicate relationship between two numbers Numbers are separated by a colon (:) Colon indicates division Numerator on left : Denominator on right Example: 1:3 is the same as 1/3 Copyright © 2022 by Elsevier Inc. All rights reserved.
- 5. Ratios: Measures in Solutions In medications Ratio of parts of drug to parts of solution = strength Safety Alert The more solution in which a drug is dissolved, the less potent it becomes Example: 1 part drug to 1,000 parts solution is more potent (stronger) than 1 part drug in 10,000 parts solution Copyright © 2022 by Elsevier Inc. All rights reserved.
- 6. Proportions An equation of two ratios of equal value Written in any of following formats Example: 3:4 = 6:8 (separated with equals) 3:4 :: 6:8 (separated with double colon) Read as “3 is to 4 as 6 is to 8” or “three fourths equals six eighths” when expressed as a fraction Copyright © 2022 by Elsevier Inc. All rights reserved.
- 7. Proportions: Means and Extremes Relationship between left and right terms is expressed by means and extremes Means = Middle Extremes = End In a true proportion, product of means is equal to product of extremes Copyright © 2022 by Elsevier Inc. All rights reserved.
- 8. Ratio and Proportion: Solving for x If three numbers in a true proportion are known, the unknown fourth number—called x—can be found x is usually placed on the left Copyright © 2022 by Elsevier Inc. All rights reserved.
- 9. Proportion: Proof 12:9 = 8:x Place the value previously obtained in the spot for x 12:9 = 8:6 Multiply means by extremes—should be equal 9(8) = 12(6) 72 = 72 Copyright © 2022 by Elsevier Inc. All rights reserved.
- 10. Ratio: Dosage Calculation Ratio is used to represent the weight of a medication that is in tablet or capsule form or in a certain volume of solution. Examples: 1 tab : 0.125 mg 1 mL : 250 mg In dosage calculation, include the unit of measurement in the dosage strength Copyright © 2022 by Elsevier Inc. All rights reserved.
- 11. Proportion: Dosage Calculation Solve for x in medication dosage calculations Example: If there are 500 mg in 1 capsule, how many milligrams are delivered in 2 capsules? 1 cap : 500 mg = 2 caps : x mg 1(x) = 500(2) 1(x) = 1,000 x = 1,000 mg Copyright © 2022 by Elsevier Inc. All rights reserved.
- 12. Case Study 1 (1 of 2) It is time to administer Ms. White’s antibiotic. Ms. White has told the provider that she has difficulty swallowing pills. An order is written for Ciprofloxacin oral suspension 450 mg PO once. You have on hand Cipro 250 mg/5 mL. Using ratio proportion, how many mL will you administer? Copyright © 2022 by Elsevier Inc. All rights reserved.
- 13. Case Study 1 (2 of 2) ANS: 9 mL Copyright © 2022 by Elsevier Inc. All rights reserved.