Grade 5 · Unit 2: Fractions, decimals and percentages

Ratio and proportion

Compare amounts and scale recipes.

Recipes use the same ratio whether cooking for 2 or 20.

Ratios in cooking

A ratio compares two amounts: 1 cup rice to 5 cups milk, 1 : 5. Scale up by multiplying both parts: 3 : 15. The taste stays the same.

Equivalent ratios

1 : 5 = 2 : 10 = 3 : 15. Ratios can be simplified like fractions: 6 : 9 = 2 : 3. A ratio is a multiplicative comparison: milk is 5 times the rice.

The unitary method

When two amounts are in proportion, find the value for one. 4 pens cost ৳60, so 1 pen costs ৳15. 7 pens cost 7 × 15 = ৳105.

Sharing in a ratio

Share ৳500 in the ratio 2 : 3. Total parts: 2 + 3 = 5. One part: 500 ÷ 5 = ৳100. Nila gets 2 parts = ৳200; Rafi gets 3 parts = ৳300.

What I learnt