Question

The Internal and external diameter of a hollow hemispherical vessel are
24cm and 25cm respectively. The cost of paint one sq.cm of the surface is 7 palse. Find the total cost to paint the vessel all over. (ignore the area of edge)​

Answer 1

Answer:

134.80

Step-by-step explanation:

Internal diameter of spherical vessel = 24 cm

External diameter of hemispherical vessel = 25 cm

Internal radius = r = 12 cm and External radius = R = 12.5 cm

Total surface area to be painted

= External curved surface + Internal curved surface + Area of ring

= 2straight piR2 + 2straight pir2 + straight pi(R2 - r2)

= straight pi(2R2 + 2r2 + R2 - r2)

= straight pi(3R2 + r2)

= 22 over 7(3 x 12.5 x 12.5 + 12 x 12)

equals 22 over 7 left parenthesis 468.75 plus 144 right parenthesis

equals 22 over 7 cross times 612.75

= 1925.78 cm2

Rate of painting = 7 paise/cm2

Thus, Cost of painting = Area x Rate = fraction numerator 1925.78 cross times 7 over denominator 100 end fraction = Rs 134. 80