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primary 6 | Maths | Geometry
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Coral
Coral

primary 6 chevron_right Maths chevron_right Geometry chevron_right Singapore

Help needed. Thanks

Date Posted: 3 years ago
Views: 287
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Try using Ratio to simplify the question:
Shaded Area to Unshaded circle B
= 25 : 100
= 1 : 4

Shaded Area to Unshaded Whole figure
= 8 : 100
= 1 : 12.5

Now both unshaded figure is 1 unit,
We can combine ratios together:
Unshaded B : Shaded Area : Unshaded whole
= 4 : 1 : 12.5

Unshaded A
= 12.5 - 4
= 8.5 units


Hence Area of A is 8.5 + 1 = 9.5 units
Area of B is 4 + 1 = 5 units
(Add the Shaded parts back to both circle)

9.5 - 5 = 4.5 units more A than B
Percentage More = 4.5/5 * 100%
= 90%
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Jasper Eng
Jasper Eng's answer
86 answers (Tutor Details)
Coral
Coral
3 years ago
Thabk you so much
Jasper Eng
Jasper Eng
3 years ago
I made a mistake:
12.5 units is the whole figure,
Hence unshaded is 11.5 units (minus 1)
Hence
Big circle should be 8.5 instead, (minus 1)
Small is 5
So 8.5 - 5 = 3.5 units MORE
3.5 / 5 * 100%
= 70% more //
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Tutor May Ho, Ex MOE Trained
Tutor May Ho, Ex Moe Trained's answer
63 answers (Tutor Details)
Whole figure refers to total unshaded area plus total shaded area. 28% means area of circle A is more by the value. To find out how many percent of Circle A more than area of Circle B, we need to do the last step, 28/40 x 100%. We are comparing area of circle A against area of circle B. Hope you understand.