Question

EXERCISE. 13.1
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:
a) The area of the sheet required for making the box.
m) The cost of sheet for it. if a sheet measuring Im-costs 30.​

Answer 1

Question :-

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 1m2 costs ₹20.

Answer :-

(i) Here, length (l) = 1.5 m, bread th(b) = 1 .25 m

and height (h) = 65 cm = 65/100 m = 0.65 m

∵ It is open from the top.

∴ Its surface area

= [Lateral surface area] + [Base area]

= [2(1 + b)h] + [lb]

= [2(1.50 + 1.25)0.65] m2 + [1.50 x 1.25] m2

= [2 x 2.75 x 0.65] m2 + [1.875] m2

= 3.575 m2+ 1.875 m2 = 5.45 m2

∴ Area of the sheet required for making the box = 5.45 m2

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

Cost of 5.45 m2 sheet = Rs. (20 x 5.45)

= Rs. 109

Hence, cost of the required sheet = Rs. 109

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