Solving Ratio Propblems

 

Introduction to Ratios for Primary School

A ratio is a way to compare two or more quantities to show how much of one thing there is compared to another. It tells us the relationship between the sizes of two groups.

Imagine you are serving food at a party. For every 3 plates of Jollof rice, you serve 2 plates of Fried rice. The ratio of Jollof rice to Fried rice is 3 to 2.

How We Write Ratios

We can write a ratio in three different ways:

• With the word "to" → 3 to 2
• With a colon symbol → 3 : 2
• As a fraction → ³⁄₂

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The Ratio Formula

Ratio = (Quantity of A) ÷ (Quantity of B)

Important Rule: Ratios should always be simplified to their lowest terms by dividing both sides by the biggest number that can go into them perfectly.

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Practice Questions

Question 1 (Easy • Fruits): In a market basket at Balogun market, there are 12 mangos and 18 oranges. What is the ratio of mangos to oranges in its simplest form?

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1. Write the initial ratio: 12 : 18
2. Find the biggest number that divides into both 12 and 18, which is 6.
3. Divide both sides by 6: (12 ÷ 6) : (18 ÷ 6) = 2 : 3

Answer: 2 : 3

Question 2 (Easy • Colored Balls): Children are playing in a playground. The ratio of green plastic balls to yellow plastic balls is 4 : 12. Simplify this ratio.

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1. Write the ratio: 4 : 12
2. Divide both numbers by their greatest common factor, which is 4.
3. (4 ÷ 4) : (12 ÷ 4) = 1 : 3

Answer: 1 : 3

Question 3 (Medium • Ice Cream Cups): At a school sports festival, vendors sold vanilla and chocolate ice cream cups in the ratio 3 : 5. If they sold 30 cups of vanilla ice cream, how many cups of chocolate ice cream did they sell?

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1. The ratio of vanilla to chocolate is 3 parts to 5 parts.
2. Since 3 parts equal 30 actual cups, find the value of 1 part: 30 ÷ 3 = 10.
3. Multiply the chocolate parts by the same number: 5 × 10 = 50.

Answer: 50 cups of chocolate ice cream

Question 4 (Medium • Plates of Rice): A caterer cooked a total of 120 plates of rice for a wedding. The plates of Jollof rice and Fried rice are shared in the ratio 5 : 3. How many plates of Jollof rice were cooked?

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1. Find the total number of parts combined: 5 + 3 = 8 parts.
2. Find the value of 1 part out of the total rice: 120 plates ÷ 8 = 15 plates.
3. Jollof rice takes 5 parts of the share: 5 × 15 plates = 75 plates.

Answer: 75 plates of Jollof rice

Question 5 (Hard • Mixed Party Items): An entertainment center sets up a kids' game arena with blue balls, red balls, and yellow balls in the ratio 2 : 3 : 5. If there are 45 red balls, what is the total number of plastic balls in the arena?

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1. Red balls correspond to the middle part of the ratio, which is 3 parts. If 3 parts = 45 balls, then 1 part = 45 ÷ 3 = 15 balls.
2. Find the total parts in the game arena together: 2 + 3 + 5 = 10 parts.
3. Multiply total parts by the value of 1 part: 10 parts × 15 balls = 150 balls.

Answer: 150 total plastic balls