Question

a solid right circular cylinder of height 1.21 m and diameter 28 cm is melted and ready into 7 equal solid cubes. Find the edge of each cube.

Answer 1

here the cylinder is melted into cube so volume of cylinder is equal to volume of cube 
the[ volume of cylinder =pi r^2 h
here the height is given as 1.21m which is 121cms
the radius of cylinder = 14cm
so volume of cylinder = 5324cm

volume of cylinder / volume of cube = number of cubes made=7

5324/a^3=7

5324/7=a^3

solving this we get a=9.12

Answer 2

Given height = 1.21m.

                      = 1.21 * 100cm

                      = 121cm

Given diameter = 28cm.

Then the radius r = 28/2

                              = 14cm.


Given that it is melted and ready into 7 solid cubes.

Therefore the volume of cylinder = 7 * volume of cubes.  ----- (1)

We know that volume of the cylinder = pir^2h  ---- (2)

We know that volume of the cube = s^3.  --- (3)

Now,

Substitute (2) & (3) in (1), we get

pir^2h = 7 * S^3

22/7 * (14) * 14 *  121 = 7 * S^3

22 * 2 * 121 * 14= 7 * S^3

74536 = 7 * S^3

74536/7 = S^3

10648 = S^3

S = 22cm.


Therefore the edge of each cube = 22cm.


Hope this helps!