General Basic Math Exams Quizzes MCQs Quizzes Percentage Math Quiz

Question:
If the radius of a circle is decreased by 50%, its area is reduced by:

Option A):
None of these
Option B):
25%
Option C):
50%
Option D):
75%

Correct Answer is Option D):
75%

Explanation:
Solution:
New radius = 50% of R = 50/100 R = R/2
New Area = π x (R/2)² =  πR²/4
Decrease = (πR² - πR²/4) = 3πR²/4
Decrease % = (3πR²/4 x 3πR² x 100) % = 75%