I would solve the above questions as follows:EC72 wrote:

Can someone help me with bii) ? Thanks in advance.

(a)

60 x 30 x 2 = 3600 (front and back)

30 x 12 x 2 = 720 ( 2 sides)

60 x 12 = 720 (base)

720 + 720 + 3600 = 5040

Alternatively,

60 x 12 + 2 x 12 x 30 + 2 x 60 x 30 = 5040

(b)

(i)

60 x 12 x 30 = 21600

(ii)

21600 - (60 - 2) x (12 - 2) x (30 - 1) = 21600 - 16820 = 4780

Alternatively,

60 x 12 + 2 x 29 x 12 + 2 x 29 x 58 = 4780,

Ans : (a) 5040 sq cm; (b)(i)21600 cubes and (ii) 4780 cubes.