How much quantity of water should be added?

Question

What quantity of water should be added to $16$ litres of $25%$ acidic solution to reduce it to $20%$ acidic solution ?

Attempt.

We have $16$ litres of solution, it has $4$ litres of acid and $12$ litres of water. Let i add $x$ litres of water to it and acid is $4$ litres. So total solution is $16+x$ litres. So I have 20% of $(16+x)= 20$ which gives me $x=4$. I am not sure though.

Thanks

Answer 1

We can solve it easily by focusing on the non-changing material , acid,

so total quantity after dilution to the required concentration = $16\cdot\frac{25}{20}$,

and thus water to be added = $16\cdot\frac{5}{20}$ = 4 litres

Answer 2

If you have 16 liters of 25% acidic water, then this implies that we have 16(0.25)= 4L of acid.

We want to know how much water we need to add to the existing 16L to obtain a solution that is 20% acid.

The 4L of acid does not change, so we can simply do 4L/0.20=20

So we must add 4 more liters of water.

Answer 3

$20 \%$ of$(16+x)=4 $,not 20(because acid content after mixing water is 4)