Question

A cylindrical tank $7km$ in diameter, contains water to a depth of $4m.$ Find the total area of the wet surface $\left(\pi =3.14\right)$

• A. $46.5m^2$
• B. $126.5m^2$
• C. $166.5m^2$
• D. $106.5m^2$

Answer 1

The correct option is B $126.5m^2$

Wet\ surface $=$ curved surface upto water level + bottom circle

Radius of the cylinder $r=\frac{7}{2}m$

Height of the cylinder $h=4m$

Area of wetted surface = Curved surface area of the cylinder + Area of base circle

$=2\pi rh+\pi r^2$

$=\pi r(2h+r)$

$=\frac{22}{7}\times \frac{7}{2}(8+3.5)$

$=11\times 11.5$

$=126.5m^2$

Hence, this is the answer.