100-liter 81334

In the morning, the waiter has 200 glasses with a volume of 0.3 liters and 100 large glasses with a volume of 0.5 liters each. He starts tapping into those glasses from the 100-liter barrel. In the evening, he will have half of the small beers and a fifth of the large ones. What % will he have left in the barrel?

Correct answer:

p =  40 %

Step-by-step explanation:

$$\begin{gathered} a=200 \\ {V}_1=0.3\text{l} \\ b=100 \\ {V}_2=0.5\text{l} \\ {V}_3=100\text{l} \\ {V}_4=\frac{a}{2}\cdot V_1+\frac{b}{5}\cdot V_2=\frac{200}{2}\cdot 0.3+\frac{100}{5}\cdot 0.5=40\text{l} \\ p=100\cdot \frac{V_4}{V_3}=100\cdot \frac{40}{100}=\frac{100\cdot 40}{100}=\frac{4000}{100}=40\% \end{gathered}$$

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