Adding 360 g water to 240 g of 15% syrup

There are 240 g of syrup at 15% concentration. After 360 g of water is added, the total becomes 600 g. What is the concentration of the diluted syrup?

Step-by-step

1. 15% × 240 = 36
   Mass of solute (unchanged by adding water or evaporating)
2. 36 ÷ 600 = 6%
   Solute ÷ new total solution = new concentration

Why it works

Adding water increases the total mass but leaves the amount of sugar unchanged, so the new concentration is the same sugar divided by the larger total mass.

Common mistakes

• Dividing the sugar by the original 240 g instead of the new total.
• Subtracting the water from the concentration.

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