Lemonade

Iva added one liter of 100% fruit juice to three liters of water, leaving two liters for Alice and Beata. She then added two more liters of water to the remaining two liters of lemonade and offered it to other friends.
a. What percentage of juice did Alena and Beata drink?
b. What percentage of juice did other friends drink?

Correct answer:

p₁ =  25 %
p₂ =  12.5 %

Step-by-step explanation:

$$\begin{gathered} S=1\text{l} \\ V=3\text{l} \\ {p}_1=100\cdot \frac{S}{S+V}=100\cdot \frac{1}{1+3}=25\% \end{gathered}$$

$$\begin{gathered} V_2=2\text{l} \\ {p}_2=100\cdot \frac{S/2}{(S+V)/2+V_2}=100\cdot \frac{1/2}{(1+3)/2+2}=\frac{25}{2}\%=12.5\% \end{gathered}$$

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