Problem: The ratio of the areas of two concentric circles is 1:3. If the radius of the smaller is r, then the difference between the radii is best approximated by:
Answer Choices:
A. 0.41r
B. 0.73
C. 0.75
D. 0.73r
E. 0.75r
Solution:
Let x be the radius of the larger circle. Then Οr2/Οx2=1/3,x=r3β, r3ββr=r(3ββ1)βΌ0.73r.