UPSC CDS Math Volume and Surface Area Questions

Let the breadth and height of the bar 9 m long be a m.
Volume of the bar =(1m)3
⇒a×a×9=1
⇒a2=

1

9

⇒a=

1

3

m
Suppose the number of exact cubes cut off from the bar be n.
∴n×(

1

3

m)3=1m3
⇒n=27
∴ Weight of each exact cube cut off =

9000

27

=

1000

3

kg