CBSE Notes, Lectures

CBSE - Mathematics - Surface Areas and Volumes

Surface Areas and Volumes

NCERT Exercise Exercise 13.6

It costs Rs 2200 to paint the inner curved surface of a cylindrical vessel 10 m deep. If the cost of painting is at the rate of Rs 20 per m2, find
(i) inner curved surface area of the vessel,
(ii) radius of the base,
(iii) capacity of the vessel.

Cost = Rs. 2200, rate = Rs. 20 per sq m, h = 10 m
Curved surface area = Cost/Rate
= 2200/20 = 110 sq cm

CSA of cylinder = 2 π rh
Or, 110 = 2 X (22/7) X r X 10
Or, r = (110 X 7)/(2 X 22 X 10) = 1.75 cm

Now, volume of cylinder = π r2 h
= (22/7) X (1.75)2 X 10 = 96.25 cubic m

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