Question

The decorative block shown in the figure is made of two solids, a cube and a hemisphere. The base of the block is a cube with edge 5 cm, and the hemisphere fixed on the top has a diameter of 4.2 cm. The total surface area of the block is ..... 

(A) 150 cm²

(B) 160.86 cm²

(C) 162.86 cm²

(D) 163.86 cm²

Answer 1

The correct option is: (D) 163.86 cm²

Explanation:

Total surface area of the block = Total surface area of cube + Curved surface area of hemisphere - Area of base of hemisphere

= 6 x (5)² + 2π x (2.1)² - π x (2.1)2 

= 150 + π x (2.1)² = 150 + 13.86 = 163.86 cm²