# Sarin, Hairu and Fatimah make greeting cards for Mother’s Day part 8 (Math Question)

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The blog postings are about the Singapore Math. The readers can learn from the postings on Solving Singapore Primary School Mathematics. You or your kids can learn dealing with Math modeling, Problem Sum from Lower Primary School to Upper Primary School level in Singapore school. This posting is a primary school math question on Shape and Area.

You can read the story of Sarin and the siblings making greeting cards for their mother by reading the posting on Sarin, Hairu and Fatimah make greeting cards for Mother’s Day in Welcome page.

You can read the posting on Sarin learns Perimeter, Area and Volume in school(Math Concept) to learn the concept of perimeter, area and volume.

Read also the posting on Sarin learns Shapes and Solids in school (Math Concept) to know about shapes.

Upper primary school mathematics question UPQ181

Sarin liked his greeting card square in shape. The design is made up of a semi circle, a quadrant and a diagonal line. He coloured the card as the figure shown. The area of the square is 784 cm2. Find the total area of the coloured parts. Express your answer correct to 2 decimal places.

Solution:

Add a red line as shown

The coloured parts can be filled as the arrows indicated

We have,

The coloured parts is ¾ of the square

The area of the square = 784 cm2

The coloured area = ¾ × 784 = 588.00 cm2

Alternative solution:

The area of the square = 784 cm2  = 28 cm × 28 cm

The length of the square = 28 cm

Take π = 22/7

The area of shape a = (784 – ¼ × π × 28 × 28) ÷ 2  = 84 cm2

The area of shape c = (½ × π × 14 × 14 – ½ × 14 × 28) ÷ 2 = 56 cm2

The area of shape b = ½ × 14 × 28 – 84 – 56 = 56 cm2

The area of the coloured parts = 784 – 84 – 56 – 56 = 588.00 cm2