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Gray Morris

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Unit One: Chapter 5

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1. Define percentage2. Convert percentages

to fractions3. Convert percentages

to decimals4. Convert percentages

to ratios

5. Convert decimals to percentages

6. Convert fractions to percentages

7. Convert ratios to percentages

8. Determine percentages from numbers

After reviewing this chapter, you should be able to:

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Used in sales tax, mortgage interest, savings earned

Used in names of medications Magnesium sulfate 50%Hydrocortisone 1%IV solution of D5W (Dextrose 5% in Water)

Used to assess level of burns Rule of Nines—Figure 5-1

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Percentage refers to how many parts are related to the whole (100 parts)

Written with the percent symbol “%” means “of 100”

5% = 5 parts of 100 parts or or 5 per 100

5100

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Figure 5-1Figure 5-1 The rule of nines for estimating burn percentage.The rule of nines for estimating burn percentage.

(From Ignatavicius D, Winkelman C, Workman M, Hausman K: (From Ignatavicius D, Winkelman C, Workman M, Hausman K: Medical-surgicalMedical-surgical

nursing: critical thinking for collaborativenursing: critical thinking for collaborative care, care, ed. 6, St. Louis, 2009, Saunders.) ed. 6, St. Louis, 2009, Saunders.)

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Intravenous (IV) solutionsPercentage = number of grams (g) of solute

(powder) in 100 mL of diluent

1,000 mL of D5W (Dextrose 5% in water)5% = 5 g in 100 mL so… 5 g in 100 mL = (x) g in 1,000 mL

100(x) = 5(1,000) x = 50 g

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Safety Point: The higher the percentage, the stronger the solutionExamples:

A 10% solution is STRONGER than a 5% solution

A 0.99% solution is WEAKER than a 1% solution

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% symbol may be used with whole numbers (15%), mixed numbers (3½%), fractions (¾%), or decimals (0.6%)

Drop % sign, place number over 100 and reduceExamples:

8 2

8%100 25

reduced

11 1 1 14% x4 100 4 100 400

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Drop % sign and move decimal two places to the left (add zeros if needed)Examples: 25% = 0.25

1.4% = 0.014Alternative Method: write as a fraction with

100 as the denominator and divide numerator by denominator

75

75% 100 75 0.75100

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Change percentage to fraction and reduce, then place the numerator on the left and the denominator on the right – separate by colonExample:

10 1

10% 1:10100 10

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Multiply the fraction by 100, reduce, add %

Example:

Alternative Method: change the fraction to a decimal, multiply by 100, add %Example:

3 100 300 75

x 75; add % 75%4 1 4 1

3

4 3 0.75 4

1000.75 x = 75; add % = 75%

1

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Move the decimal two places to the right (add zeros if needed), add %

Example:0.45 45%

2.35 235%

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Change the ratio to a fraction, then change the fraction to a percentage as described previouslyExample:

1 1 1001: 4 then x 25; add % = 25%

4 4 1

1: 4 4 1 0.25 x 100 = 25; add % = 25%

or

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Change the given percentage to a decimal or fraction, then multiply the decimal or fraction by the numberExample: A client reports he drank 25% of his

8-ounce cup of tea. Determine how much tea the client drank.

25

25% 0.25100

Multiply the decimal by the number0.25 x 8 ounces = 2 ounces

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Make a fraction with the numbers—the denominator is the number after the word “of” and the other number is the numerator

Convert to a decimal, then to a percentageExample: 12 is what percentage of 60?

12

60 12 0.2 convert to % = 20 %60

therefore 12 is 20% of 60