Topic : Area-Circle
1.
from: category_eng

1.Mathematical Writing
(1) t-r /r = .15 and t-r =0.3 . so that
0.3/ r =0.15 which means r=2.

(2) pi*t^2 - pi*r^2= pi(t^2 - r^2)=1.29 pi.
t^2 - r^2=1.29

Ans: A

1.
focus on radius
2.

3.

4.

5.
http://knowhowacademy.com/english_files/gmat/12th%20Review/problem%20solving/P175-02.gif
6.
r=10.... speed problem... but you can change it to ratio problem too..
7.

1. D
focus on radius
2. D
3. D
4. D
5. D
http://knowhowacademy.com/english_files/gmat/12th%20Review/problem%20solving/P175-02.gif
6. B
r=10.... speed problem... but you can change it to ratio problem too..
7.