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# Proportion

Math Performance Task on Proportion
Subtopics: Direct Proportion, Indirect Porportion, Maps and Scales

by

Tweet## Angie QuanHui Vanessa Isabelle Math

on 2 March 2011#### Transcript of Proportion

Proportion DIRECT PROPORTION INVERSE PROPORTION MAPS AND SCALES when 2 quantities change

by the same factor eg. a = b Directly Proportional Don't get it? (: 1 pencil cost $1. So 3

pencils costs $3. 5 pencils

cost $5. The total cost is

Directly Proportional to the number of pencils for the linguists for the visual people :D table Any graph that has a straight line is a linear graph of direct proportion Example of a linearliy increasing graph of direct proportion The cost of 1 apple is twice

the cost of an eraser. These

two items are in direct

proportion. What is your 1st impression of 'Inverse proportion'?

Sounds 'chim'? NO... You are smarter than you think. You learnt it in primary school Think of it: The more chips I eat, I become unhealthier. So technically, I know when 2 subjects are inversely proportional if:

x decreases when y increases or vice- versa So, how to apply inverse proportion in real life?

Simple. Just take for example, John takes 1 hour to do 2

Math Worksheets. So if there is only 1 Worksheet, and assuming

that he does the worksheet at a uniform rate, the time taken for

him to finish would be reduced. The time therefore is inversely proportional to the number of Worksheets John has. It takes them 2.8 days 18 men build a house in 6

days. I the number of men

become 30, and assuming they

work at the same rate, how long

will they take to build the house? Map Scale: The relationship between distances on a map and the corresponding distances on the earth's surface expressed as a fraction or a ratio Many different units

of measurement eg. 1cm

100cm on actual ground for Map scale and

1cm to 10 000cm on actual ground Reason for Map and Area Scale: A map cannot be of the same size as the length and area it represents, therefore, it is scaled down in proportion so that it can fit in a small area Large scale maps are 1:24,000 and larger.

Intermediate scale maps occur in the 1:50,000

to 1:100,000 scale range. Small scale maps are

1:250,000 and smaller. Map Scale= Map distance: Actual Distance

Area Scale= Area on Map: Actual Area A particular map shows a scale of 1 : 5000.

What is the actual distance if the map distance is 8 cm?

Map distance: Actual distance= 1: 5000

Actual distance if map distance is 8 cm= 8x 5000 cm

= 40 000 cm

= 400 m The End Thank You graph Any Questions? x y Area Scale: The relationshipbetween the area

on a map and the corresponding area on earth's

surface expressed as a fraction or ratio 2 2 Representative Fraction(RF) is the

indication of the scale eg. 1unit rep.100cm

etc. Expressed as fraction or ration and the numerator for fraction is always 1

Full transcriptby the same factor eg. a = b Directly Proportional Don't get it? (: 1 pencil cost $1. So 3

pencils costs $3. 5 pencils

cost $5. The total cost is

Directly Proportional to the number of pencils for the linguists for the visual people :D table Any graph that has a straight line is a linear graph of direct proportion Example of a linearliy increasing graph of direct proportion The cost of 1 apple is twice

the cost of an eraser. These

two items are in direct

proportion. What is your 1st impression of 'Inverse proportion'?

Sounds 'chim'? NO... You are smarter than you think. You learnt it in primary school Think of it: The more chips I eat, I become unhealthier. So technically, I know when 2 subjects are inversely proportional if:

x decreases when y increases or vice- versa So, how to apply inverse proportion in real life?

Simple. Just take for example, John takes 1 hour to do 2

Math Worksheets. So if there is only 1 Worksheet, and assuming

that he does the worksheet at a uniform rate, the time taken for

him to finish would be reduced. The time therefore is inversely proportional to the number of Worksheets John has. It takes them 2.8 days 18 men build a house in 6

days. I the number of men

become 30, and assuming they

work at the same rate, how long

will they take to build the house? Map Scale: The relationship between distances on a map and the corresponding distances on the earth's surface expressed as a fraction or a ratio Many different units

of measurement eg. 1cm

100cm on actual ground for Map scale and

1cm to 10 000cm on actual ground Reason for Map and Area Scale: A map cannot be of the same size as the length and area it represents, therefore, it is scaled down in proportion so that it can fit in a small area Large scale maps are 1:24,000 and larger.

Intermediate scale maps occur in the 1:50,000

to 1:100,000 scale range. Small scale maps are

1:250,000 and smaller. Map Scale= Map distance: Actual Distance

Area Scale= Area on Map: Actual Area A particular map shows a scale of 1 : 5000.

What is the actual distance if the map distance is 8 cm?

Map distance: Actual distance= 1: 5000

Actual distance if map distance is 8 cm= 8x 5000 cm

= 40 000 cm

= 400 m The End Thank You graph Any Questions? x y Area Scale: The relationshipbetween the area

on a map and the corresponding area on earth's

surface expressed as a fraction or ratio 2 2 Representative Fraction(RF) is the

indication of the scale eg. 1unit rep.100cm

etc. Expressed as fraction or ration and the numerator for fraction is always 1