Proportionality · TEKS 7.4A, 7.4B
Unit rates & d = rt
A unit rate tells you how much for ONE of something: miles per 1 hour, dollars per 1 ounce.
Key steps
- Unit rate = amount ÷ number of units.
- With fractions: divide by multiplying by the reciprocal.
- Distance = rate × time (d = rt). Rearranged: t = d ÷ r and r = d ÷ t.
- Better buy: compare price per unit; the lower one wins.
Worked example
Ana walks 3/4 mile in 1/4 hour. What is her speed?
- 3/4 ÷ 1/4 = 3/4 × 4/1 = 12/4 = 3.
- Answer: 3 miles per hour.
Watch out: Divide in the right order: miles ÷ hours gives miles per hour. Hours ÷ miles gives hours per mile.
Practice
5 questions with new numbers every set. Get 4 of 5 to mark this topic as practiced.