For a 20% decrease in the radius of a circle, what will be the percentage reduction in its area?

A 10%
B 20%
C 36%
D 400%

Correct Answer: 36%

Let, radius = 100 Area = πr2 = π ×1002 = 10000π New Radius = 100 - 100 ×20% = 80 New area = π (80)2 = 6400π Area decrease = ( 10000 - 6400) π = 3600π Percentage of area decrease = 3600π/10000π ×100% = 36%
Bissoy MCQ
#গণিত #শতকরা (Percentage) #Uttara Bank Ltd #Uttara Bank Ltd - Assistant Officer (Cash) - 20.05.2011

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