Question

The radius and height of a cylinder are in the ratio 5:7 and its volume is 550 cm3 . find its radius

Answer 1

Let the radius = r = 5x and height = h = 7x
So, the volume of the cylinder = π r² h
= 22/7 x (5x)² x 7x
= 22/7 x 25x² x 7x
= 22 x 25x (cube) (7 gets cancelled)
But it is given that volume = 550 cm cube
 So, 22 x 25x (cube) = 550
x (cube) = 550 / 22 x 25
x(cube) = 1 ( as 22 x 25=550 and 550 is both in nm and dm)
x = ∛1 
x = 1
so radius = 5x = 5 x 1 cm = 5cm 

Answer 2

Hope this helps..........