Question

the internal and external diameters of a hollow hemispherical vessel are 20 cm and 28 cm respectively. Find the cost of painting the vessel all over at 35 paisa per cm^2​

Answer 1

Answer: Rs. 651.19

Step-by-step explanation:

external radius (R)= 28/2=14cm

internal radius (r) = 20/2=10cm

• External surface area= 2πR²
• internal surface are = 2πr²

Total surface area= external surface area + internal surface area

                              = 2πR² +2πr²

                               = 2π(R²+r²)

                               = 2x22/7 x ( 14)² + (10)²

                                =  1860.57 cm²

cost = 1860.57 x 35/100

        = Rs 651.19