Question

.A plastic box 150cm long, 125cm wide and 65cm 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 1m2 costs Rs 20l​

Answer 1

Answer:

length of plastic box=150 cm= 1.5m

breath of plastic box=125cm=1.25m

Height =65cm=0.65 m

Since the box is open at the top, it has only five faces.

(i)

So, surface area of the box = lb + 2(bh + hl)

= 1.5 × 1.25 m2 + 2 (1.25 × 0.65 + 0.65 × 1.5) m2

= 1.875 + 2 (1.7875) m2

= (1.875 + 3.575) m2

=

5.45 m2

Hence, 5.45 m2 of sheet is required Ans.

(ii) Cost of 1 m2 of the sheet = Rs 20

∴ cost of 5.45 m2 of the sheet = Rs 20 × 5.45 m2 = Rs 109