Question

plastic box of 1.25 m long,1.05 m wide,75 depth its to be open in top ignore thickness of plastic sheet determine area of sheet required for making box also find cost of sheet isq.m= 20

Answer 1

Solution (i)

 Length of open plastic box =l=1.5 m

 Breadth of open plastic box =b=1.25 m

 Height of open plastic box =h=75 cm =75/100=0.75 m

 The area of the sheet required for making the open plastic box =lb+2bh+2hl  

(Because it is open from the top)

 =(1.5)(1.25)+2(1.25)(0.75)+2(0.75)(1.5)

=1.875+1.875+2.25

=6.00  m2

 

 

Solution (ii)

1 m2 of sheet costs Rs 20

 6.00 m2 of sheet would cost =6.00×20= Rs 120

Answer 2

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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