5. There are 24 students in a class. The ratio of boys to girls is 5 : 3. (i) How many boys are in the class? (ii) How many girls are in the class?
6. Jackie gave €100 to her daughter Kailey and asked her to spend 3 parts and save 2 parts of the total amount.
(i) Write a ratio to represent the ratio of spending to saving. (ii) How much did Kailey spend? (iii) How much did she save?
7. Ronan and Jessica are candidates in an election. They receive votes in the ratio 7 : 9. If the successful candidate receives 1 080 votes, how many votes were cast in total?
8. A recipe uses a sugar to fl our ratio of 10 : 3. If you used 70 g of sugar, how many grams of fl our would you need to use?
9. The ratio of black cars to white cars in a car park is 5 : 3. If there were 40 black cars, how many white cars were in the car park?
10. On Mr Murphy’s farm the ratio of cows to sheep is 9 : 2. If there were 72 cows on the farm, how many sheep were there?
11. The cost of a taxi is €40.50 for 15 km. Find the cost for 20 km.
12. Ramon has a part-time job in a supermarket. He earns €7 an hour during the week and €8.50 an hour at the weekend. Last week he worked 7 hours during the week and 4 hours over the weekend. How much did he earn last week?
13. I mixed up some diluted orange in two glasses. The fi rst glass had 200 ml of orange concentrate and 300 ml of water. The second glass had 100 ml of orange concentrate and 200 ml of water. Which glass has the highest concentration of orange? Justify your answer.
10.2 Scaling
By the end of this section you should be able to: ● draw scale diagrams of 2D shapes ● interpret scale diagrams
An everyday use of proportion is scaling. Scaling is the process of showing a real object with its accurate sizes reduced or enlarged proportionately by a certain amount, called the scale.
Maps and scale drawings form a crucial part of everyday life. Scale drawings are useful in a variety of careers from surveyors, to town planning and architecture.
Scale diagrams (or drawings) are often used to represent a smaller or larger object, shape or image. The scale used will depend on the reduction or enlargement of the object.
Section A Introducing concepts and building skills