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19. An aquarium is in the form of a cuboidwhose external measures are 80 cm x 30cm x 40 cm.The base,side faces and backface are to be covered with a colouredpaper.Find the area of the paper needed.(A) 2000 cm2 (B) 8000 cm2(C) 3000 cm2 (D) 1000 cm2cmCnm27 |
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Answer» we calculate the area total the acquarium:Atot=2(ab+ah+bh)=2(80×30 +80×40 + 30×40); =2×(2400+3200+1200); =2×6800=136000 cm²we calculate the area of front face:Af=a×h=80×40=3200 cm²we calculathe the area of the top:At=a×b=80×30=2400 cm²we calculate the area of paper needed:A=Atot-(Af+At)=136000-(3200+2400)=136000-5600=8000 cm² therefore answer is (B) 8000 cm² |
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