## Task 1 - 290811

On a bottle of standard 40 percent acetic acid, the following instructions are given: "The contents of this bottle ( $200 \mathrm{ml}$ ), mixed with $800 \mathrm{ml}$ of water, yield a ten percent vinegar."

Is this correct?
The content of this bottle of vinegar essence consists of $\frac{40}{100} \cdot 200 \mathrm{ml}=80 \mathrm{ml}$ acetic acid and $200 \mathrm{ml}-80 \mathrm{ml}=$ $120 \mathrm{ml}$ water.

After mixing with the specified $800 \mathrm{ml}$ water, there are consequently a total of $920 \mathrm{ml}$ water and 80 $\mathrm{ml}$ acetic acid present. This makes $920 \mathrm{ml}+80 \mathrm{ml}=1000 \mathrm{ml}$ of liquid, of which $80 \mathrm{ml}$ is acetic acid. In $100 \mathrm{ml}$ of this liquid, there are thus $8 \mathrm{ml}$ of acetic acid; i.e., it is an 8 percent vinegar.