Question

Read the following passage and answer the questions given at the end :
Students of Class XII presented a gift to their school in the form of
an electric lamp in the shape of a glass hemispherical base surmounted by
a metallic cylindrical top of same radius 21 cm and height 3.5 cm. The top
was silver coated and the glass surface was painted red..
c) What is the cost of silver coating the top at the rate of 75 per 100 cm??
(ii) What is the surface area of glass to be painted red ?

Answer 1

coating = 92.4Rs

surface area to be painted red = 2772cm2

Step-by-step explanation:

Area to be coated with silver = 2πrh+πr2=πr(2h+r)

=22/7×21(7+21)

=66×28

=1848cm²

Cost of silver coating=1848/100 × 5

=92.5Rs

Surface area to be painted red = 2πr²

=2×22/7×21×21

=2772cm²

Answer 2

Answer:

a) cost of silver coating the top at the rate of rupee 5 per 100 cm^2 is 18.48 × 5 = 92.4

b) surface area of glass to be painted red is 2772

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