Question

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Answer 1

Question :-
A open box is made of wood 3 cm thick. Its external length,breadth, and height are 1.46 m, 1.16 m and 8.3 dm respectively what is the cost of painting the inner surface at 50p per 100 square centimetre

Solution :- Thickness of open box =  3 cm  =  0.03 m

External  length (L) = 1.46 m

⇒  Internal length  (l) = 1.46m – 2 × 0.03m = 1.4m

External breadth (B) = 1.16 m

⇒  Internal breadth (b) = 1.16m – 2 × 0.03m = 1.1m

External height (H) = 8.3 dm  =  0.83m

⇒  Internal height (h) = 0.83 m – 0.03m =  0.8m


Inner surface area  =  lb + 2lh + 2bh

=  1.4m × 1.1m + 2 × 1.42m × 0.8m + 2 × 1.1m × 0.8m

1.560m2 + 2.272m2 + 1.76m2

=  5.592m2

cost of painting 1m2  =  Rs 50

⇒  cost of painting inner surface area  =  Rs 50 × 5.592 = Rs 296