Question

The rain which falls on a roof 18 m long and 16.5 m wide is allowed to be stored in a cylindrical tank 8 m in diameter. If it rains 10 cm on a day, what is the rise of water level in the tank due to it?

Answer 1

Length of the water on a roof = 18 m
Breadth of the water on a roof = 16.5 m
Height of the water on a roof = 10 cm=0.1 m
Volume of the water on a roof = Length $\times$ Breadth $\times$ Height = 18 m $\times$ 16.5 m $\times$ 0.1 m = 29.7 m³
Since water is to be stored in the cylindrical tank, the volume of water on a roof is equal to the volume of a cylindrical tank.
Volume of cylindrical tank = πr²h = 29.7 m³
$h=\frac{29.7}{{\displaystyle \frac{22}{7}}\times (4{)}^2}=0.5906\mathrm{m}=59.06\mathrm{cm}$
Thus, the rise of water level in the tank is 59.06 cm.