From a solid cylinder whose height is 2.4 cm and diameter is 1.4 cm, a conical cavity of same height and same diameter is carved out. The total surface area of the remaining solid is : (Use $\pi=\frac{22}{7}$)
Answer & explanation
Correct answer: option 2
Curved surface area of cylindrical part
Remaining surface area of solid = Curved surface area of cylindrical part + Curved surface area of conical part + Area of circular base
= 2πrh + πrl + πr²
= 2 × \(\frac{22}{7}\) × 0.7 × 2.4 + \(\frac{22}{7}\) × 0.7 × 2.5 + \(\frac{22}{7}\) ×
( 0.7) ²
= \(\frac{22}{7}\) × 0.7 ( 2 × 2.4 + 2.5 + 0.7 )
= \(\frac{11}{5}\) × ( 8 )
= \(\frac{88}{5}\)
= 17.6
The correct answer is Option (2) → $17.6 ~cm^2$