Question

Water is flowing into a cuboidal reservoir at the rate of 70 litres per minute. If the volume of the reservoir is 126 cubic metres, find the number of hours it will take to fill the reservoir.

Answer 1

Given :-

• Water is flowing into a cuboidal reservoir at the rate of 70 litres per minute.

• The volume of the reservoir is 126 cubic metres

To Find :-

• Find the number of hours it will take to fill the reservoir.

Solution :-

~Here, we're given the volume of the reservoir and the speed of water flowing in it. Firstly we need to convert the volume given to us in litres as the speed given to us is 70 liters per min . Then , we can easily find the time taken .  

Conversion of volume :-  

→ 1 m³ = 1000 L  

→ 126 m³ = 126 × 1000  

= 126000 L  

Now,  

$\sf \bullet \;\; Time\;taken\;for\;70\;L = 1\;mins$

 

$\sf \bullet \;\; Time\;taken\;for\;1\;L = \dfrac{1}{70}$

By unitary method :-  

$\sf \implies Time\;taken\;for\;126000\;L = \dfrac{1}{70} \times 126000$  

$\sf \implies 1 \times 18000$

$\sf \implies 18000\; mins$

Conversion into hours :-  

$\sf \bullet \;\; 1\;min = \dfrac{1}{60} \; hr$

$\sf \implies 18000\;mins = \dfrac{18000}{60}$

$\sf \implies 300\; hours$

Therefore,  

• Time taken by water will be 300 hours  

Answer 2

Given Question :-

• Water is flowing into a cuboidal reservoir at the rate of 70 litres per minute. If the volume of the reservoir is 126 cubic metres, find the number of hours it will take to fill the reservoir.

Answer

Given :-

• Water is flowing into a cuboidal reservoir at the rate of 70 litres per minute.

• The volume of the reservoir is 126 cubic metres

To Find :-

• Number of hours it will take to fill the reservoir.

Concept Used :-

• 1 litre = 1000 cubic cm.

or

• 1 cubic metre = 1000 litres

And

• 1 hour = 60 minutes

$\large\underline{\bold{Solution :- }}$

• Let time taken be 't' minutes.

Now,

• Volume of reservoir = 126 cubic metres = 126000 litres

Also,

• Water is flowing in to it at the rate of 70 litres per minute.

So,

• Water flow in 't' minutes = 70 t litres

Now,

$\large \underline{\bf \: { According \: to \: statement }}$

$\rm :\longmapsto\:70t = 126000$

$\rm :\implies\:t = 1800 \: minutes$

$\bf :\implies\:t = \dfrac{1800}{60} = 3 \: hours$