A plastic box 1.5 m long, 1.25 m wide and 65 cm deep is to be made. It

1.	A plastic box 1.5 m long, 1.25 m wide and 65 cm deep is to be made. It is opened at the top. Ignoring the thickness of the plastic sheet, determine(i) the area of the sheet required for making the box.(ii) the cost of sheet for it, if a sheet measuring 1 m2 costs Rs. 20.
Answer» Here we are given that (i) Length of plastic box (l) = 1.5 m Breadth of plastic box (b) = 1.25 m Height of plastic box (h) = 65 cm = 0.65 m Since box is open at the top. Therefore total surface area of the plastic box (open at the top) = lb + 2bh + 2hl = [1.5 x 1.25 + 2(1.25 x 0.65 + 0.65 x 1.5)] m² = [1.875 + 2(0.8125 + 0.975)] m² = [1.875 + 2 x 1.7875] m² = [1.875 + 3.575] m² = 5.450 m² Hence, area of the plastic sheet required for making the box is 5.450 m². (ii) Cost of 1 m² plastic sheet = Rs. 20 Cost of 5.45 m² plastic sheet = Rs. 5.540 x 20 = Rs. 109

A plastic box 1.5 m long, 1.25 m wide and 65 cm deep is to be made. It is opened at the top. Ignoring the thickness of the plastic sheet, determine(i) the area of the sheet required for making the box.(ii) the cost of sheet for it, if a sheet measuring 1 m2 costs Rs. 20.

Answer»

Here we are given that

(i) Length of plastic box (l) = 1.5 m

Breadth of plastic box (b) = 1.25 m

Height of plastic box (h) = 65 cm

= 0.65 m

Since box is open at the top.

Therefore total

surface area of the plastic box (open at the top)

= lb + 2bh + 2hl

= [1.5 x 1.25 + 2(1.25 x 0.65 + 0.65 x 1.5)] m²

= [1.875 + 2(0.8125 + 0.975)] m²

= [1.875 + 2 x 1.7875] m²

= [1.875 + 3.575] m²

= 5.450 m²

Hence, area of the plastic sheet required for making the box is 5.450 m².

(ii) Cost of 1 m² plastic sheet = Rs. 20

Cost of 5.45 m² plastic sheet

= Rs. 5.540 x 20

= Rs. 109