From a circular sheet of paper with a radius of 20 cm, four circles of radius 5cm each are cut out. What is the ratio of the uncut to the cut portion?
[1] 1 : 3
[2] 4 : 1
[3] 3 : 1
[4] 4 : 3
Answer:
The area of the original paper is (pi)(20)2 = 400(pi).
The area of the cut portion is 4 (pi)(5)2 = 100(pi).
Thus the area of the uncut portion is 300(pi).
The required ratio is 300(pi): 100(pi), i.e. 3 : 1.
