option d
lets assume are of outer circle as 100pi
equate 100pi=pi*r^2 after that we get radius as 10 units
from fig. we know that R+r=10...........(1)
from problem we have given relationship of area of outer and inner circle is 5/8
(area of two inner circle )/area of outer circle=5/8
x/100pi=5/8
x=62.5pi
for inner circles,
Area of larger circle +area of smaller circle=62.5pi
R^2+r^2=62.5
after simplifying and substituting value of R=10-r from equation (1)
we will get two values of r=7.5,2.5
after getting these two value we have to take smaller value
and substitute in equation 1 and get value of R=7.5
R/r=7.5/2.5=3:1