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Probability

Question
CBSEENMA9003430
Wired Faculty App

7.A joker’s cap. is in the form of a right circular cone of base radius 7 cm and height 24 cm. Find the area of the sheet required to make 10 such caps. 

Solution

Base radius (r) = 7 cm
Height (h) = 24 cm
therefore space Slant height (l) = square root of straight r squared plus straight h squared end root
            equals square root of left parenthesis 7 right parenthesis squared plus left parenthesis 24 right parenthesis squared end root equals square root of 49 plus 576 end root equals square root of 625 equals 25 space cm
therefore space space Curved surface area of a cap = πrl
         equals 22 over 7 cross times 7 cross times 25 equals 550 space cm squared

∴ Curved surface area of 10 caps = 550 x 10 = 5500 cm2
Hence, the area of the sheet required to make 10 such caps is 5500 cm2.

Some More Questions From Probability Chapter

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 1 m2 costsर 20.

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 र 7.50 per m2.

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?

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?

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)    How much of tape is needed for all the 12 edges?

Parveen wanted to make a temporary shelter for her car, by making a box-like structure with tarpaulin that covers all the four sides and the top of the car (with the front face as a flap which can be rolled up). Assuming that the stitching margins are very small, and therefore negligible, how much tarpaulin would be required to make the shelter of height 2.5 m, with base dimensions 4 m × 3 m?

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