Tank - fuel prices

I have a car with a 50-litre tank. I want to calculate the weighted average price of a full tank of fuel at the end of the year. In December, 30 litres were filled at 37.50 CZK per litre, and in November, 40 litres at 38.40 CZK per litre. What is the weighted average price per litre and the value of a full tank?

Final Answer:

c =  38.0143 Kc/l
x =  1900.7143 Kc

Step-by-step explanation:

$$\begin{gathered} V=50\text{l} \\ {V}_1=30\text{l} \\ {c}_1=37.50\text{Kc/l} \\ {V}_2=40\text{l} \\ {c}_2=38.40\text{Kc/l} \\ c=\frac{V_1\cdot c_1+V_2\cdot c_2}{V_1+V_2}=\frac{30\cdot 37.5+40\cdot 38.4}{30+40}=38.0143\text{Kc/l} \end{gathered}$$

$x=c\cdot V=38.0143\cdot 50=1900.7143\text{Kc}$

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