Question

A big iron boiler tank opened on top is cylindrical in shape. It's height is $10$ m and radius is $7$ m. It gets corroded at a rate of $3$ sq. meter/day. The number of days in which it totally gets corroded is $(\text{Take}\pi =\frac{22}{7})$

• A. 192
• B. 202
• C. 198
• D. 208

Answer 1

The correct option is C

198

Surface area of the boiler = Curved Surface area + Bottom area
$=2\pi rh+\pi r^2$
$=2\times \frac{22}{7}\times 7\times 10+\frac{22}{7}\times 7^2$
$=594$ sq. meter
Total no. of days $=\frac{\text{Total Surface Area of the tank}}{\text{Area corroded per day}}=\frac{594}{3}=198$