Skills for working life Fractions

Skills for working lifeFractions

Outcomes from this sessionAt the end of this session you should be able to Understand the relationship between unit fractions and division when finding parts Understand that there are different strategies for finding fractional parts

What is a fraction? Definition ‘ A Part of a whole’

Comparing Fractions Before you can compare fractions the bottom (denominator) must be the same. e.g. Which is the smaller 5 OR 1 8 2 This becomes 1 x 4 = 4 2 4 8 4 Is smaller than 5 8 8 Therefore 1 is smaller 2

Comparing Fractions Which is smaller? 1 or 3 4 8 1 X 2 = 2 4 2 8 1/4 is smaller than 3/8

Comparing Fractions Which is smaller? 1. 2 or 6 5 10 Answer 2 x 2 = 4 5 2 10 2 is smaller than 6 5 10 2. 5 or 3 8 4 Answer 3 x 2 = 6 4 2 8 5 is smaller than 3 8 4

Questions • Which is the larger? • 1 7 3 • 3 8 4 • 2. 1 11 • 3 6 8 All can divide into 24 82118 24 24 24 All can divide into 24 843 24 24 24

Fractions In a fraction the bottom number is the denominator. This is the number that you divide by to find one part e.g. To find 1/5 , divide by 5 In a fraction the top is the numerator this shows how many parts e.g. to find 2 , divide by 5 , multiply by 2 5 2 of 20 1 of 20 = 4 5 5 But we have 2 4 x 2 = 8 5

Fractions 4 of 30 5 Divide by 5 , then multiply by 4 1 of 30 = 6 5 6 x 4 = 24

Questions 1. 2 of 15 7. 1 of 30 5 3 2. 4 of 15 8. 2 of 30 5 3 3. 3 of 50 9. 1 of 99 5 3 4. 2 of 50 10. 2 of 99 5 3 5. 3 of 40 11. 1 of 27 5 3 6. 5 of 40 12 2 of 27 8 3 6 10 12 20 30 33 20 66 24 9 25 18

Application Tony is having a Greek party for 40 people. Unfortunately 10 people decide to cancel, so he will need to reduce his food order to fit. He was going to order 1 Stifado 3 Hummus and 2 drinks of Ouzo for each person How does Tony do his calculations?

Original order is for 40 people New order 30 people He needs only 30 of the food 40 30 Is the same as 3 40 4 e.g. 3 hummus x 40 = 120 total But we only need 3 4 First work out ¼ of 120 = 30 30 X 3 = 90 hummus are now required

Group work In pairs , work out how many stifado and drinks Tony will now need? Original = 40 x 1 = 40 stiffido ¾ of 40 = ¼ of 40 = 10 3 x 10 = 30 stifado are now required Drink = 40 x 2 drinks = 80 total ¾ of 80 = ¼ of 80 = 20 3 x 20 = 60 drinks required

Questions • As a group or with another person , try these • My order for a party of 20 people who wanted three sandwiches and two drinks each has been changed to a party of 15. • What should my order be? Sandwiches • drinks 45 30

2. My order for 60 meals had to be changed when I was told that 2/3 of the people were vegetarians. How many vegetarian meals did I need to order ? 3. ¾ of the 120 meals I was asked to cook had to be chicken How many was that ? 4. 1/3 of the 600 meals that I make each month are vegetarian. How many meals do I make with meat? 40 90 400

3. In a car assembly there are 160 built per hour. The table below shows the colours that were ordered in an hour. RED BLUE BLACK SILVER GREEN 3 16 1 16 1 8 3 8 1 4 • Was green or silver colour the most popular • Was red or blue the most popular • What do all the fractions add up to? • Out of the 160 cars , 100 are 1.6 litre engines. What fraction is that? Silver Blue 1 100/160 = 5/8

4. Change the following into fractions of 1 hour? • 30 mins • 10 mins • 45 mins • d. 5 mins 30 = 1 60 2 10 = 1 60 6 45 = 3 60 4 5 = 1 60 12

Tim filled in his time sheet as follows: 7 1/2 7 3/6 6 2/3 6 4/6 7 1/6 7 1/6 21 1/3 hours Fill in the last column to show the mixed fraction. How many hours did he claim in total (as a mixed fraction).

Skills for working life Fractions