# The radius of two concentric circles is in the ratio 2:5, then find out the ratio between their areas.

The radius of two concentric circles is in the ratio 2:5, then find out the ratio between their areas.

I cannot solve this GMAT. Please help me. Tell me which is the correct answer?

a. 2:5

b. 5:2

c. 4:25

d. 25:4

e. None of the above

Thanks you very much for your question. Your questions was – The radius of two concentric circles is in the ratio 2:5, then find out the ratio between their areas.

According to the question,

the radius of two concentric circles is in the ratio 2:5.

The standard formula to calculate the area of a circle (A) = Πr2, where r is the radius of the circle.

Since, p is a constant, we can say that A is directly proportional to the square of the

radius.

∴ A1 : A2 = r12 : r22 = (2)2 : (5)2 = 4 : 25

Hence, the correct answer is option c.

Hope you understand this Math question. if you have more questions then Ask here.

You can also visit my website: http://knowledgeworldbd.com

Find me on facebook, twitter & Google Plus