Ever wondered why Mama's jollof tastes the same every time?
Ngozi's mother always uses 2 cups of rice for every 3 cups of water. Whether she cooks for 4 people or 40, she keeps that ratio of 2 : 3 — so the jollof is never too soggy or too dry.
Revision notes
Compare quantities with ratios, simplify them, and share money fairly in a given ratio.
Ngozi's mother always uses 2 cups of rice for every 3 cups of water. Whether she cooks for 4 people or 40, she keeps that ratio of 2 : 3 — so the jollof is never too soggy or too dry.
A ratio compares two (or more) quantities of the same kind. Rice to water = 2 : 3 means 2 parts rice for every 3 parts water.
Order matters: rice : water = 2 : 3, but water : rice = 3 : 2.
A ratio is written without units, so both quantities must be in the same unit first: 50 kobo to ₦2 is 50 kobo to 200 kobo = 50 : 200.
🔑 Key idea: A ratio a : b compares a parts with b parts of the same kind.
Just like equivalent fractions, you can divide both parts by the same number without changing the ratio.
12 : 18 — the HCF of 12 and 18 is 6, so 12 : 18 = 2 : 3.
50 : 200 — divide both by 50 to get 1 : 4. A ratio is in its simplest form when the parts have no common factor except 1.
🔑 Key idea: Divide both parts by their HCF to simplify.
To share ₦6,000 between Tunde and Bola in the ratio 2 : 3, first add the parts: 2 + 3 = 5 parts.
One part is ₦6,000 ÷ 5 = ₦1,200. Tunde gets 2 × ₦1,200 = ₦2,400 and Bola gets 3 × ₦1,200 = ₦3,600.
Check: ₦2,400 + ₦3,600 = ₦6,000 ✓. If you know one person's share instead, use it to find one part first.
🔑 Key idea: Total parts → value of one part → multiply.
₦1,600 is shared between Tunde and Yusuf in the ratio 5 : 3. How much does Yusuf get?
Step 1: Total number of parts
5 + 3 = 8
Step 2: Value of one part
₦1,600 ÷ 8 = ₦200
Step 3: Yusuf's share
3 × ₦200 = ₦600
Answer: ₦600
Ready to check you've got it? Scroll up and work through the lesson: the interactive visuals, practice questions and mastery check are all there.