Question

A scientist has 400ml of a 8% solution. How much water needs to be added to lower it to a 2% solution?

Answer 1

Answer:

1,200 ml of water must be added

Step-by-step explanation:

Let

x ----> the amount of water needed  in ml

we know that

In a 8% solution, the amount of water is 92%

so

$400(0.92)=368\ ml$

In a 2% solution the amount of water must be 98%

so

$(400+x)0.98=368+x$

solve for x

$392+0.98x=368+x\\x-0.98x=392-368\\0.02x=24\\x=1,200\ ml$