Question

a fish tank can hold 45 litres of water when filled to the brim it is 4/9 filled if 2/5 of the water is removed how much more water must be added in order to fill the tank to the brim?

Answer 1

Total capacity of tank = 45lt
It is 4/9 filled = 4/9(45) = 20 lt
Now 2/5 water is removed= 2/5(20)
= 8lt
Remaining water = 20 - 8 = 12lt

Now
To fill it to the brim = 45- 12 = 33lt

I.e 33lt more water needs to be added

Answer 2

The capacity of the fish tank = 45 litres

At present the tank is 4/9 is filled with water ,

means , now it contains = $\frac{4}{9}$ × 45 = 4 × 5= 20 liters of water

According the question, if 2/5 of the water is removed,

first we have to find out the quantity of removed water.

Hence the quantity of removed water = $\frac{2}{5 }$ × 20 = 2 ×4= 8 litres of water.

At present remaining quatity of water in that fish tank = (20 - 8) = 12 litres.

Now the quantity of water must be added in order to fill the tank to the brim = ( 45 - 12) litres

        = 33 litres

Ans :- 33 litres of water must be added to fill the fish tank to the brim.