Five pumps

Three same pumps fill the tank with 50400 liters of diesel in 7 hours. How many liters of diesel will it take in 4 hours if we add two more of the same pumps and pump them the same way?

How much more (or less) will they get if we add 2 of the same pumps and all work for 4 hours?

Correct answer:

V₁ =  48000 l
d =  -2400 l

Step-by-step explanation:

$$\begin{gathered} V_0=50400\text{l} \\ Q=50400/7/3=2400\text{l/h} \\ {V}_1=4\cdot (3+2)\cdot Q=4\cdot (3+2)\cdot 2400=48000\text{l} \end{gathered}$$

$d=V_1-V_0=48000-50400=-2400\text{l}$

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