Question 1043633
Volume of original=pi*r^2h
Volume of new=pi*(1.1r)^2*(h-kh)
pi*1.21r^2*(h-kh)=1.089*pi^r^2*h
The pi cancels, the r^2 cancel
1.21(h-kh)=1.089h
1.21h-1.21kh=1.089h
0.121h=1.21kh
the h cancel
0.121=1.21k
k=0.121/1.21=0.10 or 10% 
B
Let r=10 and h=20
volume of original is pi*100*20=2000pi
volume of new is pi*121*18=2178pi, which is 0.089 or 8.9% larger