Question

the radius of a brass plate is 20 cm.find the cost of polishing the top surface of 12 such plates at the rate of rupees 450 per m
take
$\pi3.14$
​

Answer 1

Answer:

Rs. 101.736

Step-by-step explanation:

given,

r=20 cm

area of top surface= CSA of hemisphere

                              =3$\pi$r²

                               = 3 × 3.14 × 20cm

                              = 188.4 cm²

area of 12 such plates = 12×188.4

                                     = 2260.8 cm²

rate= 450 / m²

      = 450/ 10000cm²

cost of polishing= 450/ 10000cm² × 2260.8 cm²

                          = Rs. 101.736

i hope this helps you...