A family in Singapore part 9 (Math Question)

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You can click here and read the posting on A family in Singapore about Sarin’s family.

You should read the posting on Sarin learns Average Number, Percentage and Charting in school (Math Concept) to understand the concept of Percentage.

Upper primary school mathematics question UPQ148

Sarin’s mother is keeping track of the household expenses. She need to make sure the family’s expenditure is within their means. The line chart below shows their family’s expenditure over five weeks. When was there a 20% decrease in their family’s expenditure?

 Solution:

                The percentage of decrease is the percentage of decrease in expenditures of two consecutive weeks to the expenditure of the first week of the two weeks.              

                Base on the line-chart, we can tabulate a table with the weekly decreases and compute the percentage of decreases.

                Example:

                The different in expenditure from 1st week to 2nd week = 90 – 80 = $10

                The percentage decrease = 10 ÷ 90 × 100% = 11.1%

 

 

Expenditure ($)

Decrease ($)

Decrease (%)

1st week

90

 

 

2nd week

80

10

11.1

3rd week

50

30

37.5

4th week

40

10

20.0

5th week

20

20

50.0

 

                        From the table, the family expenditure decrease by 20%  from 3rd week to 4th week.

More  questions on Average, Percentage and Charts. Click here…

More questions on Problem Sum. Click here…

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