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Q : 8    A bus stop is barricaded from the remaining part of the road, by using 50 hollow cones made of recycled cardboard. Each cone has a base diameter of 40 cm and height 1 m. If the outer side of each of the cones is to be painted and the cost of painting is Rs 12 per \small m^2, what will be the cost of painting all these cones? (Use \small \pi =3.14 and take \small \sqrt{1.04}=1.02)
 

Given, hollow cone. The base diameter of the cone =  Height of the cone =   Slant height =  We know, Curved surface area of a cone =  The curved surface area of 1 cone =   The curved surface area of 50 cones Now, the cost of painting  area =   Cost of the painting  area Therefore, the cost of painting 50 such hollow cones is 

Q : 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.
 

Given, a right circular cone cap (which means no base) Base radius of the cone =  Height We know, Curved surface area of a right circular cone  The curved surface area of a cap =  The curved surface area of 10 caps =  Therefore, the area of the sheet required for 10 caps = 

Q : 6    The slant height and base diameter of a conical tomb are 25 m and 14 m respectively. Find the cost of white-washing its curved surface at the rate of Rs 210 per \small 100\hspace{1mm}m^2.
 

Given, a conical tomb The base diameter of the cone =  Slant height We know, Curved surface area of a cone Now, Cost of whitewashing per  =  Cost of whitewashing per  =  Therefore, the cost of white-washing its curved surface of the tomb is 

Q : 5    What length of tarpaulin 3 m wide will be required to make conical tent of height 8 m and base radius 6 m? Assume that the extra length of material that will be required for stitching margins and wastage in cutting is approximately 20 cm (Use \small \pi =3.14).
 

Given, Base radius of the conical tent =  Height of the tent =  We know, Curved surface area of a cone =   Area of tarpaulin required = Curved surface area of the tent Now, let the length of the tarpaulin sheet be Since  is wasted, effective length = Breadth of tarpaulin =   Therefore, the length of the required tarpaulin sheet will be 63 m.

Q : 4     A conical tent is 10 m high and the radius of its base is 24 m. Find

            (ii) cost of the canvas required to make the tent, if the cost of \small 1\hspace{1mm}m^2 canvas is Rs 70.

Given,  Base radius of the conical tent  =  Height of the conical tent =   Slant height =  We know, Curved surface area of a cone   Curved surface area of the tent  Cost of  of canvas =  Cost of  of canvas = Therefore, required cost of canvas to make tent is 

Q : 4     A conical tent is 10 m high and the radius of its base is 24 m. Find

            (i) slant height of the tent.

Given,  Base radius of the conical tent  =  Height of the conical tent =   Slant height =  Therefore, the slant height of the conical tent is 

Q : 3    Curved surface area of a cone is \small 308\hspace{1mm}cm^2 and its slant height is \small 14\hspace{1mm}cm. Find

             (ii) total surface area of the cone.

Given, The curved surface area of a cone =   Slant height The radius of the cone is   (ii) We know, Total surface area of a cone = Curved surface area + Base area Therefore, the total surface area of the cone is    

Q : 3    Curved surface area of a cone is \small 308\hspace{1mm}cm^2 and its slant height is 14 cm. Find

           (i) radius of the base 

Given, The curved surface area of a cone =   Slant height (i) Let the radius of cone be  We know, the curved surface area of a cone=    Therefore, the radius of the cone is 

Q : 2    Find the total surface area of a cone, if its slant height is \small 21\hspace{1mm}m and diameter of its base is \small 24\hspace{1mm}m

Given,  Base diameter of the cone =  Slant height =  We know, Total surface area of a cone = Curved surface area + Base area   Required total surface area of the cone=

Q : 1    Diameter of the base of a cone is \small 10.5 \hspace{1mm}cm and its slant height is \small 10 \hspace{1mm}cm. Find its curved surface area.
 

Given,  Base diameter of the cone =  Slant height =  We know, Curved surface area of a cone   Required curved surface area of the cone=
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