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Question 7: Shanti Sweets Stall was placing an order for making cardboard boxes for packing their sweets. Two sizes of boxes were required. The bigger of dimensions 25 cm × 20 cm × 5 cm and the smaller of dimensions…
Read MoreQuestion 6: A small indoor greenhouse (herbarium) is made entirely of glass panes (including base) held together with tape. It is 30 cm long, 25 cm wide and 25 cm high. (i) What is the area of the glass? (ii)…
Read MoreQuestion 5: A cubical box has each edge 10 cm and another cuboidal box is 12.5 cm long, 10 cm wide and 8 cm high. (i) Which box has the greater lateral surface area and by how much? (ii) Which…
Read MoreQuestion 4: The paint in a certain container is sufficient to paint an area equal to 9.375m2. How many bricks of dimensions 22.5 cm × 10 cm × 7.5 cm can be painted out of this container? Question 3 Question…
Read MoreQuestion 3: The floor of a rectangular hall has a perimeter 250 m. If the cost of painting the four walls at the rate of Rs. 10 per m2 is Rs. 15000, find the height of the hall. [Hint :…
Read MoreQuestion 2: The length, breadth and height of a room are 5 m, 4 m and 3 m respectively. Find the cost of white washing the walls of the room and the ceiling at the rate of Rs. 7.50 per…
Read MoreQuestion 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: (i) The area of the sheet required…
Read MoreExample 2: Hameed has built a cubical water tank with lid for his house, with each outer edge 1.5 m long. He gets the outer surface of the tank excluding the base, covered with square tiles of side 25 cm…
Read MoreExample 1: Mary wants to decorate her Christmas tree. She wants to place the tree on a wooden box covered with coloured paper with picture of Santa Claus on it (see Fig. 13.4). She must know the exact quantity of…
Read MoreDerivation of Heron’s formula: This formula has been named after the Egyptian mathematician Heron. This famous formula is about finding the area of a triangle when its all three sides are given. It is derived from the formula of area…
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