Question

Water is flowing at the rate of $25$ kilometer per hour through a cylindrical pipe radius $7$ m into a rectangular tank which is $30$ m long and $12$ m wide. In how many hours will the water level in the tank raise by $10$ m?

• A. $1$ hour
• B. $2$ hours
• C. $3$ hours
• D. $4$ hours

Answer 1

The correct option is A $1$ hour

Speed of water $=25$ m/hr
volume of the water discharged = cross section area of the pipe $\times$ time $\times$ speed
Volume of water discharged in one hour= $\pi r^2\times 1\times 25$
$=3850$
Volume of the required quantity of water in the tank is,
$lbh=30\times 12\times 10=3600$
Volume of water discharged in $T$ hours $=$ required quantity of water in the tank
$3850T=3600$
$T\approx 1$ hour
Hence, it will take $1$ hour to raise the required water level.