If the radius of a circle is decreased by 30 percent, by what percent will the area of the circular region decrease?

A 15%
B 49%
C 51%
D 60%

Correct Answer: 51%

Initial radius = R Initial area =  π R2 New radius = R - 30% of R = R - 0.3R = 0.7R New area =  π (0.7R)2 = 0.49 π R2 Decrease in area = (πR2 -   0.49πR2) / (πR2) × 100% = 51%
Bissoy MCQ
#গণিত #শতকরা (Percentage) #Bangladesh Development Bank Ltd #Bangladesh Shilpa Bank Ltd - Officer - 2004

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