RATIO

Back to: Mathematics Primary 5

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A ratio is used to compare two quantities. It is usually represented with the symbol (:). A ratio just like fractions has two parts which are NUMERATOR and DENOMINATOR. Ratio can also be reduced to its lowest term.

EXAMPLE

1. Write the ratio of 16 to 28 in its lowest form.

Solution

2. In a bus, there are 9 women and 15 men. Find the ratio to the simplest form of the number of:
3. Men to women
4. Women to men
5. People to men

Solution

3. Express 350m as a fraction of 1km in its lowest form.

Solution

4. John is 27 years old. His brother James is 15 years old. What is the ratio of John’s age to his brother age? In 6 years-time, what will be the ratio of James’ age to John?

Solution

John’s age to James’ age = John’s age : James’ age

In 6 years-time,

John’s age = 27 + 6 = 33

James’ age = 15 + 6 = 21

James’s age to John’s age = 21:33

 

PROBLEMS ON RATIO

One of the most common use of ratio is in sharing. It plays an important role in everyday’s activity such as sharing money between or among people.

Example

1. Alex and Charles were instructed by their parents to share a pocket money of N600 in the ratio of 3:5. How much does each receive?

Solution

Total ratio = 3 + 5

= 8

Charles share = N600 – N225

= N375

2. The angles in a triangle are in the ratio 1:2:3. Find the largest angle.

Solution

The total angles in a triangle = 180⁰

Total ratios = 1 + 2 + 3

= 6

Largest ratio = 3

 

3. Emmanuel and Isaac shared some money in the ratio of 4: 5 respectively. If Emmanuel got N120, how much did Isaac get?

Solution

Emmanuel : Isaac

4         :      5

120        :      x

Cross multiply.

Total money shared = N120 + N150

= N270

4. Karisa and Hope saved some money in the ratio 6:4. If Hope saved N280, how much did Karisa save?

Solution

Karisa : Hope

6      :    4

X     :    280

Total money saved = N280 + N420

= N700

Quiz

1. In a box, there are 20 balls. 6 are red, 10 are green and 4 are blue
2. What is the ratio of red to green balls?
3. What is the ratio of green to blue balls?
4. What is the ratio of blue to red balls?
5. What is the ratio of red balls to the total number of balls?
6. Mary finished her chores in 2hours 3omins. The following day, Martha finished hers in 1hour 30mins. Find the ratio of time taken Mary to Martha.
7. In a basket filled with oranges and mangoes, the ratio of mangoes to all the fruits is 9:13. If the basket contains 154 fruits:
8. How many are mangoes?
9. How many are oranges?
10. Ojo shared an amount of money between Paul and Peter in the ratio 3:5. If Peter received N100. Find:
11. How much Paul received
12. The total amount shared between them.

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