Sea water

Seawater contains about 4.3% salt. How many dm³ of distilled water we must pour into 5 dm³ of sea water to get water with 1.8% salt?

Result

V =  6.94 dm³

Solution:

$4.3 \% \cdot \ 5 = 1.8 \% \cdot \ (5+V) \ \\ 4.3/100 \cdot \ 5 = 1.8/100 \cdot \ (5+V) \ \\ \ \\ 4.3 \cdot \ 5 = 1.8 \cdot \ (5+V) \ \\ \ \\ 1.8V = 12.5 \ \\ \ \\ V = \dfrac{ 125 }{ 18 } \doteq 6.944444 \ \\ = 6.94 \ dm^3$

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