Question

24) Find the cost of time coating the open cylinder of radius 7cm and height 20cm at the rate of Rs 5/cm2.​

Answer 1

Answer:

surface area] + [Base area]

= [2(l + b)h] + [l × b]

= [2(1.50 + 1.25)0.65 m2] + [1.50 × 1.25 m2]

= [2 × 2.75 × 0.65 m2] + [1.875 m2]

= 3.575 m2 + 1.875 m2 = 5.45 m2

∵ The total surface area of the box = 5.45 m2

∴ Area of the sheet required for making the box = 5.45 m2

(ii) Rate of sheet = Rs. 20 per m2

Cost of 5.45 m2 = Rs. 20 × 5.45

⇒ Cost of the required sheet = Rs.109

Answer 2

Answer:

we know the height in 15cm

And radius is 7cm

Now the csas of polishing per m² is 5rupees

Now 660X5

=3300

There fore the cost of polishing the ctclindrical tower is

rupees 3300