Maths

1.
The ratio of the volume of two cubes
=320:135
=64:27
The The ratio of the length of two cubes
=∛64:∛27
=4:3
2(a)
Let the original volume be x
after drinking the water , the remaining volume of the water is given by (1-27.1%)x=0.729x
The ratio of the radius of the remaining right conical and the original's
=∛0.729x:∛x
=0.9:1
So the new radius of the remaining right conical : the original's =0.9:1
So the the percentage decrease in the radius of water surface
=(1-0.9)/1*100%=10%
(b)

The ratio of the wet surface area of the remaining right conical and the original's
=0.9^2:1^2

=0.81:1
percentage decrease in the wet surface area
=(1-0.81)/1*100%
=19%