The dimensions of the tank = 12m x 8m x 6m
Total area of the required sheet = 2(12x6 + 8x6) + 12x8
= 336 squre meter
Width of the shhet = 4 meter
Required length of the sheet = L
ATQ Lx4 = 336 => L = 84 meter
The cost of an iron sheet = Rs.17.50 per metre
The total cost of an iron sheet = 17.50x84 = Rs 1470