# Sarin learns Perimeter, Area and Volume in school part 99 (Math Question)

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The blog postings are about the Singapore Math. The readers can learn from the postings about Solving Singapore Primary School Mathematics. The blog presents the Math Concept, the Math Questions with solutions that teaches in Singapore Primary Schools. You or the kids can acquire the skill of dealing with the Math Modeling, the Math Problem Solving and the Problem Sum from Lower Primary School to Upper Primary School level after reading the blog postings. This posting is an upper primary school math question on Ratio, Shapes, Percentage and Area.

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

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

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

Also to read the posting on Sarin learns concept of ratio in school to understand the concept of Ratio.

Challenge yourself with the question before look out for the given solution‼!

Upper primary school mathematics question UPQ452

The circle below is divided into 4 parts, A, B, C and D. Part A and part C form one semi-circle. Part B and part D form the other semi-circle. The area of part A to the area of part C is in the ratio of 1 : 3. The area of part B to the area of part D is in the ratio of 1 : 2.

(a) What percentage of the whole circle is part D?

(b) The area of part C is bigger than part B by 20 cm2. Find the area of the whole circle. Solution:

The area ratio,

B : D : (D + B) = 1: 2 : 3 = 4 : 8 : 12

A : C : (A + C) = 1 : 3 : 4 = 3 : 9 : 12

A and C form semicircle as well as B and D form semicircle

The area (A + C) = The area (D + B)

Therefore,

A : B : C : D : (A + C ) : (B + D) : (A + B + C + D) = 3 : 4 : 9 : 8 : 12 : 12 : 24

The percentage of whole circle is part D = 8/24 × 100% = 33.33%

The area of part c is bigger than the area of part B by 20cm2 5 units = 20

1 unit = 4 cm2

The area of the whole circle = 4 × 24 = 96cm2

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