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# Proportion and Fractions

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## Mr Mattock

on 3 September 2016

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#### Transcript of Proportion and Fractions

Proportion and Fractions
Proportion as Fractions
In the top set maths class, the ratio of boys to girls is 2:3.

(a) What fraction of the class are boys?

(b) What is the relationship between the number of boys and the number of girls?
Starter
This diagram shows that the ratio of the lengths of blue rods to red rods is 2:1 (i.e. that blue is of red).

What fraction of the total length of this bar does blue represent?

How could we tell that from the ratio?
Proportion and Fractions
L.O. - To write proportions as fractions, and manipulate
the fractional representation.

1
2
There are always two different fractional view points in a proportional relationship.

One quantity is a fraction of the other; i.e. the blue is half of the red.

Each quantity is a fraction of the total; i.e. the blue is a third of the total length.
Proportion as Fractions
In the top set maths class, the ratio of boys to girls is 2:3.

(a) What fraction of the class are boys?

(b) What is the relationship between the number of boys and the number of girls?
2
5
The number of boys is the number of girls
2
3
OR The number of girls is
1
times more than the boys.
1
2
Proportion as Fractions
What fraction
of the people were
'Other'?

What is the relationship between the people eating Pork and Beef?
Proportion as Fractions
What fraction
of the people were
'Other'?

What is the relationship between the people eating Pork and Beef?
80
2
360
9
=
OR The number of people who eat Beef is 3 x greater than the
number of people who eat Pork
The number of people who eat Pork is of the number of people who eat Beef
4
15
3
4
Main Activity 1
Complete the Proportion and Fractions RAG sheet.
Red: (1) (i) 3/7 (ii) There are 3/4 as many vowels as
consonants.
(2) (i) 8/15 (ii) There are 7/8 as many boys as girls.
(3) (i) 8/21 (ii) Charles walks 8/13 of the distance
before his friends house that he walks after.
(4) (i) 2/5 (ii) Sam has 2/3 of the money that Vishal
has.
(5) (i) 3/10 (ii) The volume of juice is 3/7 of the
Amber: (6) (i) 3/8 (ii) The volume of yellow paint is 3/5 of
the volume of blue paint.
(7) (i) 1/6 (ii) The length of the shorter side is 5/12
of the middle side and 5/13 of the longer side.
(8) (i) 2/5 (ii) The distance driven after Shane's
break is 2/3 of the distance driven before.
(9) (i) 3/7 (ii) Usman will get 3/4 of the sweets
that Jack will get.
Green: (10) (i) 3/14 (ii) The shorter length is 3/4 of the
longer length.
(11) (i) 1/5 (ii) 7/9 of the number of people who get
the bus walk to school.
(12) (i) 5/12 (ii) The green section has 3/4 the number of questions of the amber sections and 3/5 the number of questions in the red section.
Starter
This diagram shows that the ratio of the lengths of blue rods to red rods is 1:2 (i.e. that blue is of red).

What fraction of the total length of this bar does blue represent?
1/3

How could we tell that from the ratio?
There are 1 out of 3 parts in the ratio on the blue side.
1
2
Activities
Key Examples
Activity