Question

a cylindrical drum which is open at the top has a diameter 140 cm and height 1.2 metre find the cost of Electro planting this drum from the inside at rupees 7.50 per metre square​

Answer 1

The cost of  Electroplating this drum is Rs. 51.15

Step-by-step explanation:

diameter of the cylinder = 140 cm = 1.40 m

radius of the cylinder = 0.7 cm

height of the cylinder = 1.2 m

area for electroplating = curved surface area of the cylinder + area of the base

curved surface area of the cylinder =$2\pi rh$

= $2\times\frac{22}{7}\times(0.7)\times (1.2)$

= 5.28 cm²

area of the base = $\pi r^{2}$

= $\frac{22}{7}\times (0.7)^2$

= 1.54 cm²

then total area for electroplating =  5.28 + 1.54  = 6.82 cm²

cost of electroplating 1 m² = Rs. 7.50

cost of electroplating 6.82 m² = 6.82 ×7.50 = 51.15 rupees

hence,

The cost of  Electroplating this drum is Rs. 51.15

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