Question

The radius of a circular brass plate is 20 cm. Find the cost of polishing the top surface of 12 such plates at the rate of Rs 450 per sq. m. (take pi 3.14)

Answer 1

area of 1 brass plate= $\pi r^{2}$
                                =3.14*20*20
area of 12 such plates= 12*3.14*400
rate= rs 450 per 10000 sq. cm
cost= 4800*3.14*45/1000
       = 678.24 rs