Solve problems involving rates.
Number Framework Stage 8
Comparing by Finding Rates (Material Master 8-28)
Problem: “Julie drives 210 kilometres in 3 hours, and Marie drives 340 kilometres in 5 hours. Who is driving faster on average?”
Discuss how far Julie and Marie travel in 1 hour.
(Answer: 210 ÷ 3 = 70 km/h, 340 ÷ 5 = 68 km/h. So Julie is travelling faster.)
Problem: “A 500 gram packet of Wheatie Flakes costs $1.85, and a 800 gram packet of Wheatie Flakes costs $2.88. The supermarket shows the costs in cents per 100 grams. What do the labels show? Which packet is better value?”
(Answer: 185 cents ÷ 5 = 37 cents per 100 grams. 288 cents ÷ 8 = 36 cents per 100 grams. So the bigger packet is better value.)
Problem: “Gather data about different sized packets of a product from a supermarket.
Compare their value by finding the cost in cents per 100 grams for each of the sizes.”
Examples: Worksheet (Material Master 8–28).
Understanding Number Properties:
k grams of flour costs $ j. How would you work out the cost of flour per 100 grams? (Answer: $100j/k per 100 grams)