Problem: When the circumference of a toy balloon is increased from 20 inches to 25 inches, the radius is increased by:
Answer Choices:
A. 5 in.
B. 221β in.
C. 5/Ο in.
D. 5/2Ο in.
E. Ο/5 in.
Solution:
Since C=2Οr, letting r2β be the original radius, r1β the final radius, we have 25β20=2Οr1ββ2Οr2β=2Ο(r1ββr2β);β΄r1ββr2β=5/2Ο.