Problem: If the base of a rectangle is increased by 10% and the area is unchanged, then the altitude is decreased by:
Answer Choices:
A. 9%
B. 10%
C. 11%
D. 1191%
E. 9111%
Solution:
bh=(1011b)(xh)∴x=1110 and h is reduced by 111 or 9111%;
or
bh=(b+101b)(h−100rh)=bh+101bh−100rbh−1000rbh
∴101−100r−1000r=0 and r=9111 (per cent).