CAT 1996 — QA Question 5
Basics of Mensuration/PrismEasy
From a circular sheet of paper with a radius 20 cm, four circles of radius 5 cm each are cut out. What is the ratio of the uncut to the cut portion?
Answer & solution
Correct answer: 3 : 1
- A
1 : 3
- B
4 : 1
3 : 1
- D
4 : 3
Solution
Area of the original paper = π(20)2 = 400π cm2. The total cut portion area = 4(π)(5)2 = 100π cm2 . Therefore, area of the uncut (shaded) portion = (400 – 100) = 300π cm2.
Hence, the required ratio = 300π : 100π = 3 : 1.