Multiple choice

If the diameter of a circle is decreased by 50%, find the percentage decrease in its area. यदि एक वृत्त के व्यास में 50% की कमी की जाती है, इसके क्षेत्रफल में प्रतिशत कमी ज्ञात कीजिए।

  1. 50%

  2. 100%

  3. 65%

  4. 75%
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

If diameter decreases by 50%, the radius also decreases by 50%. Area = πr². If new radius = 0.5r, new area = π(0.5r)² = 0.25πr² = 25% of original. This represents a 75% decrease. Many students incorrectly think 50% diameter decrease means 50% area decrease.

Keep practicing — related questions