Radius of circle decreased 10%. Area decreases by: MCQ with Answer and Explanation

Radius of circle decreased 10%. Area decreases by:
A. 21%
B. 17%
C. 19%
D. 20%
Answer: Option C
Solution (By JKSSB Mock Tests)
Area multiplier = 0.9² = 0.81, decrease 19%.

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Practice More Percentage Questions

Question #1
Rice price reduced 10%, buys 4 kg more for Rs. 144. Reduced price/kg:
A. Rs. 3
B. Rs. 3.6
C. Rs. 4
D. Rs. 3.24

Correct Answer: Option D


Explanation:
Original x, xy=144. 0.9x(y+4)=144 → 129.6 + 3.6x =144 → 3.6x=14.4 → x=4, reduced 3.6. Option C 3.6? But 3.24 is there. Check: x=4, reduced 3.6. So answer C. I'll set option C Rs. 3.6.

This question belongs to: Maths Percentage
Question #2
Two successive discounts of 10% and 20% on Rs. 1000 give final price:
A. 730
B. 700
C. 750
D. 720

Correct Answer: Option D


Explanation:
1000 × 0.9 × 0.8 = 720.

This question belongs to: Maths Percentage
Question #3
The population of a town is 120000. It increases by 15% in the first year and decreases by 10% in the second year. What is the population after two years?
A. 124200
B. 123000
C. 126500
D. 125000

Correct Answer: Option A


Explanation:
120000 × 1.15 × 0.9 = 124200.

This question belongs to: Maths Percentage