Question

$6$ pipes are required to fill a tank in $1$ hour $20$ minutes. How long will it take if only $5$ pipes of the same type are used?

• A. $56$ minutes
• B. $80$ minutes
• C. $96$ minutes
• D. $72$ minutes

Answer 1

The correct option is C $96$ minutes

It is given that $6$ pipes are required to fill a tank in $1$ hour $20$ minutes.

$6$ pipes can fill a tank in minutes $=(60+20)min=80min$

Let $5$ pipes can fill a tank in $xmin.$

Since, it is an inverse proportion,

$\Rightarrow$ $6\times 80=5\times x$

$\Rightarrow$ $x=\frac{6\times 80}{5}$

$\Rightarrow$ $x=\frac{480}{5}$

$\therefore$ $x=96$ minutes

$\therefore$ $5$ pipes can fill a tank in $96min.$