Given that side of a cube = 10cm
Total Surface Area of cube = 6(side)2
= 6 × 10 × 10
= 600cm2
Now, Radius of hemisphere = 3.5cm
Curved Surface Area of hemisphere = 2πr2 = 2 x 22/7 x 3.5 x 3.5
= 77cm2
Base area of hemisphere = Area of circle = πr2
= 22/7 x 3.5 x 3.5
= 38.5cm2
Therefore,
Total Surface Area of block = Total Surface area of a cube + CSA of the hemisphere - Base area of a hemisphere
= 600 + 77 – 38.5
= 638.5cm2
Cost of painting the block of 1cm2 = Rs 0.50
Cost of painting the block of 638.5cm2 = Rs 0.50 × 638.5
= Rs 319.25