Godolphin & Latymer, 2011 sample paper, Q 40

[earleymom]

A set of 5 squared boxes are made from centimetre cubes and each box fits exactly inside each other, with the tops level. The dimensions of the largest box is 14cm X 14cm X 13cm

c) How many cubes are used to make the third box

The dimensions of the third box would be 10cm X 10cm X 11cm


On face 1(F1), total number of cubes = 10 * 11 = 110
On the opposite face of F1, total number of cubes = 10 * 11 = 110
On the adjacent face of F1 = F1A, total number of cubes = (10 -2) * 11 = 88
On the opposite face of F1A, total number of cubes =(10 -2) * 11 = 88
On the bottom of the cube, total number of cubes = (10 -2) *(10 -2) = 64

So, total number of cubes will be: 460

Am I correct? Is there any other easy way to explain this to a child?

Thanks...

[stevew61]

Work out the volume of the third box and subtract the volume of the fourth box? Less calculations so less errors.

[stevew61]

(10*10*11) - (8*8*10)

1100 - 640


460

[earleymom]

Yes, that is a simple solution, thanks stevew61