Subject
Quantitative Aptitude
Topic
Circles
For a 20% decrease in the radius of a circle, what will be the percentage reduction in its area?
For a 20% decrease in the radius of a circle, what will be the percentage reduction in its area?
ক)
10%খ)
20%গ)
36%ঘ)
400%Explanation
If R is the original radius then the area of the circle is =πr2 If we decrease the radius by 20% the new radius is =.8r so the new area is=π .(8r)2 = .64πr2 Compute the percent of the new to the old: = 64πr2 / πr2=.64 The decrease then is 100 - 64 = 36%Related questions
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