Question

The radii of three concentric circles are in the ratio of 1:3:4 what is the ratio of the area between the two inner circle to that between the two outer circle​

Answer 1

Step-by-step explanation:

Given The radii of three concentric circles are in the ratio of 1:3:4 what is the ratio of the area between the two inner circle to that between the two outer circle

• So we have concentric circles which are in the ratio 1 : 3 : 4. We need to find ratio of area between two inner circle to that between two outer circle.
• Required ratio will be  
•                                   = π [ (3 r)^2 – r^2] : π [(4 r)^2 – (3 r)^2]
•                                     = 9 r^2 – r^2 : 16 r^2 – 9r^2
•                                     = 8 r^2 : 7 r^2
•                                      = 8 : 7

Therefore the required ratio is 8 : 7.