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Exercise 13.1, , Lion 1. A plastic box 1.5 m long, 1.25 m wide, , ; and 65 cm deep is, Fade. It is opened at the top. Ignoring the thic, , kness of the plastic, , | mne cost of sheet for it, if a sheet measuring 1m’ costs € 20,, , ion We have a plastic box of, 1=length= 15m, b= width= 1.25 m, , h=depth= 65cm, 65, =—m=065 m H-tm=4, 100 ( m= 100 cm), Surface area of the box = 2(Ib + bh+ hl), , = 2(1.5x 1.25 + 1.25 x 0.65 + 0.65 x 1.8), , = 2(1.875+ 0.8125 + 0.975) = 2 (3.6625), =7.325m? ,, , '} Area of the sheet required for making the box, , =7.325 -Ixb (. Box is opened at the top), , =7.325- 1.5x 1.25=7.325 - 1875 =5.45 me, j/steet measuring 1 m? costs = 2.. ° ¢ Ao, , * Sheet measuring 5.45 m? costs = %20x 5.45 =%109, , “ 2. The length, breadth and height of a room are 5 m, 4m, 0, , ‘spectively. Find the cost of white washing the walls of the, ind the ceiling at the rate of 77.50 per m’., , We have a room of =7=5m, b=4m

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te, , , , , , Question 6. A small indoor greenhouse (, of glass panes (including base) held together with tape. It ig : e, 25 em wide and 25 cm high. 0 tm goa, , (i) What is the area of the glass?, , (ii) How much of tape is needed for all the 12 edges?, Solution Dimension for herbarium are, , l= 3b om, b= 25 cmandh= 25 cm, Area of the glass = 2(Ixb+ bxh+ hy !, = 2(30x 25 + 25x 25 4 25,, , = 2(750 + 625 + 750) = 2 (2125), , ) = 42502, Length of the tape = 4 (+ b + h)= 4(304 25 4 25) 4, [Herbarium is a shape of cuboid len, , = 4x 80= 320cm, , Question 7. Shanti Sweets Stalll was placing an order, cardboard boxes for packing their sweets. Two Sizes of boxes it, required. The bigger of dimensions 25 cm x 20 cm x5 cm and, smaller of dimensions 15 cm x 12cm x 5 cm: For all the Overlap, a, of the total surface area is required extra. If the cost of, , the cardbig, is 4 for 1000 cm’, find the cost of cardboard Tequired for suppigy, “250 boxes of each kind. ;, , herbarium is, , 4, , gth= 44, bg, , for map, , Solution *Oimension for bigger box, / = 25 om, b = 20 cmandh=5 om ial, 3 y, Total surface area of the bigger size box “er, , =2(/xb+bxh+hx), = 2(25 x 204+ 20x5 +5 x 25), = 2600+ 100+ 125), = 2(725) = 1450 cm?, Dimension for smaller box, 7=15 cm b=12 cmandh=5 cm, Total surface area of the smaller size box = 2(15 x 12 + 12x5 +5x 15), , = 2 (180 + 60+ 75) = 2 (315)=60, P= 2x 2080 om? =104 on?, 100 ' ?, , ‘, , Area for alll the overlaps =5% x 2080 cm, , Total surface area of both boxes and area of overlaps, , : = (2080+ 104) cm? = 2184 cm?, Total surface area for 250 boxes = 2184 x 250 om?, , Cost of the cardboard for 1000 om? = 24, ,, Costs of the cardboard for dom? = 7, , ‘ 1000, Cost of the cardboard for 2184 x 250 cm? = af 2184 x.260 = %2184, , 4009, aA

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jon 8. Parveen wanted to make a temporary shelter for her car., mgnaking a box-like structure with tarpaulin that covers all the four, 7, and the top of the car (with the front face as a flap which can be, ; up). Assuming that the stitching margins are very small and, re negligible, how much tarpaulin would be required to make the, er of height 2.5 m, with base dimensions 4 m x 3 m?, , jon Dimension for shetter, /=4m,o=S3mandh=25 cm - 25 ™, , Required area of tarpaulin to make the shelter, = (Area of 4 sides + Area of the top) of the car, | = 2(F + D)xh+ (x db), 4 . = 2(44+ 3)x 25+ (4x3) ° 7, — =(2x7x25)+ 12=35 + 12=47 mr