The weight of a wooden box made of wooden planks with the thickness 5 cm along with its covering is 115.5kg. But the weight of the box filled with rice is 880.5 kg. The length and breadth of inner side of the box are 12 dcm and 8.5 dcm respectively and the weight of 1 cubic dcm rice is 1.5kg. Let us write the inner height of the box after calculation. Let us calculate the total expenditure ot colour the outside of the box, if the rate is Rs. 1.50 per sq.dcm.

Weight of rice inside the box = (880.5-115.5) kg. = 765 kg.

Volume of the box =\frac{765}{1.5}= 510 cu. dcm.

Let the height of the box = h dcm.

According to the problem,

12 × 8.5 × h = 510

h =\frac{510}{12 × 8.5} = 5 dcm.

Outside length of the box = (12+2 × 0.5) = 13 dcm.

Outside breadth of the box = (8.5+2 × 0.5) = 9.5 dcm.

Outside height of the box =(5+2 × 0.5)=6 dcm.

Total outside surface area of the box

= 2(13 × 9.5+13 × 6+9.5 × 6) sq. dcm.

= 2(123.5+78+57) = 2 × (258.5) = 517 sq. dcm.

∴ Total cost for painting the outside surface area

= 517 × Rs. 1.50 = Rs. 775.50