Medical Dosage Calculations A Dimensional Analysis Approach Eleventh Edition Chapter 5 Converting from One System of Measurement to Another

Learning Objectives 5.1 State the equivalent units of weight between the metric and household systems. 5.2 State the equivalent units of volume between the metric and household systems. 5.3 State the equivalent units of length between the metric and household systems. 5.4 Convert a quantity measured in metric units to its equivalent measured in household units. 5.5 Convert a quantity measured in household units to its equivalent measured in metric units. Slide 2 is list of textbook LO numbers and statements

Equivalents of Common Units of Household and Metric Measurement (1 of 3) Table 5.1 Approximate Equivalents between Metric and Household Units of Volume, Weight, and Length blank Metric Household Volume 5 milliliters (mL) ≈ 1 teaspoon (t) 15 milliliters (mL) 1 tablespoon (T) 30 milliliters (mL) 1 ounce (oz) 240 milliliters (mL) 1 cup 500 milliliters (mL) 1 pint (pt) 1,000 milliliters (mL) 1 quart (qt) Weight 1 kilogram (kg) 2.2 pounds (lb) Length 2.5 centimeters (cm) 1 inch (in)

Equivalents of Common Units of Household and Metric Measurement (2 of 3) Table 5.2 Summary Table of Equivalents within and Approximate Equivalents between Metric and Household Units of Volume 1 teaspoon ≈ 5 mL 1 tablespoon = 3 teaspoons 15 mL 1 ounce = 2 tablespoons = 6 teaspoons 30 mL 1 cup = 8 ounces = 16 tablespoons 240 mL 1 pint = 2 cups = 16 ounces 500 mL 1 quart = 2 pints = 4 cups = 32 ounces 1,000 mL = 1 L

Equivalents of Common Units of Household and Metric Measurement (3 of 3) Note: Here are some useful equivalents: 6 t = 2 T = 1 oz = 30 mL

Figure 5.1 Medication cups showing equivalent units.

Figure 5.2 Medication cup filled to 10 mL.

Equivalents of Common Units of Household and Metric Measurement Example 5.1 (1 of 2) Convert 8 teaspoons to an equivalent volume measured in milliliters.

Equivalents of Common Units of Household and Metric Measurement Example 5.1 (2 of 2)

Equivalents of Common Units of Household and Metric Measurement Example 5.2 (1 of 2) Convert 60 milliliters to an equivalent volume measured in ounces.

Equivalents of Common Units of Household and Metric Measurement Example 5.2 (2 of 2)

Equivalents of Common Units of Household and Metric Measurement Example 5.3 (1 of 2) A patient weighs 150 pounds. What is the patient’s weight measured in kilograms?

Equivalents of Common Units of Household and Metric Measurement Example 5.3 (2 of 2)

Equivalents of Common Units of Household and Metric Measurement Example 5.4 (1 of 3) An infant weighs 4 kilograms. What is the infant’s weight measured in pounds and ounces? First convert 4 kg to pounds: 4 kg = ? lb

Equivalents of Common Units of Household and Metric Measurement Example 5.4 (2 of 3) The equivalence needed for the unit fraction is 1 kg = 2.2 lb

Equivalents of Common Units of Household and Metric Measurement Example 5.4 (3 of 3) Now, convert 0.8 lb to ounces.

Equivalents of Common Units of Household and Metric Measurement Example 5.5 (1 of 4) A tumor has a diameter of 2 inches. What is the diameter of the tumor measured in millimeters? 2 in = ? mm First change the inches to centimeters

Equivalents of Common Units of Household and Metric Measurement Example 5.5 (2 of 4)

Equivalents of Common Units of Household and Metric Measurement Example 5.5 (3 of 4) Now, change 5 cm to millimeters. 5 cm = ? mm To convert centimeters to millimeters is a jump of 1 place to the right.

Equivalents of Common Units of Household and Metric Measurement Example 5.5 (4 of 4) So, in 5 cm, move the decimal point 1 place to the right.

Chapter Summary (1 of 2) It is important to memorize all the equivalences for volume, weight, and length between the metric and household systems of measurement. Dimensional Analysis can be used to perform conversions between the metric and household systems. The equivalences between systems are not exact equivalences; they are approximate equivalences.

Chapter Summary (2 of 2) When performing conversions between two systems, your answers are not exact; they are approximate. When performing conversions between two systems, answers may differ somewhat, depending upon which approximate equivalences are used.