Problem: The radius of the first circle is 1 inch, that of the second 1/2 inch, that of the third 1/4 inch and so on indefinitely. The sum of the areas of the circles is
Answer Choices:
A. 3Ï€/4
B. 1.3Ï€
C. 2Ï€
D. 4Ï€/3
E. none of these
Solution:
S=π+4π​+16π​+⋯,S=π/[1−(1/4)]=4π/3.