Chapter 7: Unit Conversions (Proportion method)
If a student weighs 80 kg, howmuch does he weigh in pounds?
Step 1. Find a conversion factor that relates the units of interest to one another (page 34 table).
1 kg ≈ 2.205 pounds
Chapter 7: Unit Conversions
If a student weighs 80 kg, howmuch does he weigh in pounds?
Step 2. Express the conversion factor as a ratio (fraction):
1 kg 2.205 pounds
Chapter 7: Unit Conversions (Proportion method)
Chapter 7: Unit Conversions
If a student weighs 80 kg, howmuch does he weigh in pounds?
Step 3. Express the problem as aratio with an unknown:
80 kg ?
Chapter 7: Unit Conversions (Proportion method)
Chapter 7: Unit Conversions
Step 4. Set up a proportion equation such that the units in bothnumerators are the same and the units in both denominators are thesame:
80 kg ?
Chapter 7: Unit Conversions (Proportion method)
1 kg 2.205 pounds
=
Chapter 7: Unit Conversions
Step 5. Solve for the unknown:
80 kg (2.205 pounds)
Chapter 7: Unit Conversions (Proportion method)
1 kg =?
= 176.4 pounds?
Chapter 7: Unit Conversions
Step 6. Check that the answer makes sense
Chapter 7: Unit Conversions (Proportion method)
= 176.4 pounds?
Chapter 7: Unit Conversions (Unit canceling method)
Convert 2.80 kg to pounds.
Step 1. Write the problem as an equation.
2.8 kg = ? pounds
Chapter 7: Unit Conversions
Convert 2.80 kg to pounds.
Step 2. Find a conversion factor such that the units cancel (page 34).
1 lb 0.454 kg
Chapter 7: Unit Conversions (Unit canceling method)
Chapter 7: Unit Conversions
Convert 2.80 kg to pounds.
Step 3. Place the conversion factor into the equation.
2.80 kg X = ?
Chapter 7: Unit Conversions (Unit canceling method)
1 lb 0.454 kg
Chapter 7: Unit Conversions
Step 4. Solve the equation; multiply 2.80 kg by the conversion factor:
Chapter 7: Unit Conversions (Unit canceling method)
2.80 kg X ≈ 6.17 lb 1 lb 0.454 kg
Chapter 7: Word Problems Requiring Multiple Steps
Transgenic sheep can secrete a human protein,AAT, into their milk. AAT is valuable in the treatment of emphysema. The concentration of AAT in the milk is 15 g/L. A sheep can produce 400 liters of milk each year. AAT isworth $110/gram. What is the value of a year’sproduction of AAT from such transgenic sheep?
= $?/year400 L year
15 g L
X$110gram
X
= $660,000/year
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