Q. 74.4( 16 Votes )
A factory manufactures 120000 pencils daily. The pencils are cylindrical in shape each of length 25 cm and circumference of base as 1.5 cm. Determine the cost of colouring the curved surfaces of the pencils manufactured in one day at Rs. 0.05 per dm2.
The pencil is in shape of cylinder.
Let the radius of base be r cm
Circumference of base = 1.5 cm
2πr = 1.5 cm
[As Circumference of circle is 2πr]
Also, Height, h = 25 cm
As we know,
Curved surface area of cylinder = 2πrh
Where r is base radius and h is height
1 cm = 0.1 dm
1 cm2 = 0.01 dm2
37.5 cm2 = 0.375 dm2
Cost for coloring 1 dm2 = Rs. 0.05
Cost for coloring 0.375 dm2 (i.e. 1 pencil) = Rs. 0.01875
Cost for coloring 120000 pencils = 120000 ×0.01875 = Rs. 2250
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