Learn how two quantities change together in proportion, and solve real problems using ratios, the rule of three, and unit conversion.
The rule of three lets you find an unknown value when three related values are known, by setting up a proportion between two ratios.
If 5 workers can build a wall in 12 days, how many days would 3 workers take?
5×12 = 3×d → d = 60/3 = 20 days
If 3 kg of rice costs ₹180, what is the cost of 7 kg?
180/3 = 60 per kg; 7×60 = ₹420
Quantities can be divided unequally in a given ratio, and units can be converted using proportional relationships between measurement systems.
Divide ₹800 between two people in the ratio 3:5.
Total parts=8; each part=100; shares are ₹300 and ₹500
Convert 15 miles to kilometres if 1 mile ≈ 1.6 km.
15×1.6 = 24 km
1. If 4 machines produce 200 items in a day, how many items would 6 machines produce in a day?
2. If 8 pens cost ₹96, what is the cost of 12 pens?
3. Divide ₹1,200 between three people in the ratio 2:3:5.
4. 6 workers finish a job in 15 days. How many days would 9 workers take?
5. Convert 50 km into miles if 1 mile ≈ 1.6 km.