Proportionality · TEKS 7.4E
Converting measurement systems
To convert between customary units (inches, miles, pounds) and metric units (cm, km, kg), use the conversion fact you are given.
Key steps
- Write the fact as a rate, for example 2.54 cm per 1 inch.
- Going to the smaller unit, multiply. Going to the bigger unit, divide.
- Check: the number of small units should be the bigger number.
Worked example
1 mile ≈ 1.61 km. How many miles is a 10 km race?
- A mile is bigger than a km, so expect fewer miles: divide.
- 10 ÷ 1.61 ≈ 6.2.
- Answer: about 6.2 miles
Watch out: Multiplying when you should divide gives 16.1 miles, which is more miles than kilometers. That can’t be right.
Practice
5 questions with new numbers every set. Get 4 of 5 to mark this topic as practiced.