yoomi
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I dont understamd this problem please help------!

A work crew has a new pump and an old pump. The new pump can fill a tank in 5 hours, and the old pump can fill the same tank in 7 hours. Write and solve and equation for the time it will take both pumps to fill one tank of the pumps are used together.

Respuesta :

caylus
Hello,

Let's [tex]D_1\ the \ outflow\ of\ the\ new\ pump\\ D_2\ the \ outflow\ of\ the\ old\ pump\\\\ V \ the\ volume \of\ the\ tank\\\\ D_1*5=V==\ \textgreater \ D_1= \dfrac{V}{5} \\ D_2*7=V==\ \textgreater \ D_2= \dfrac{V}{7} \\ D_1+D_2= \dfrac{V}{5}+ \dfrac{V}{7} \\ D_1+D_2= \dfrac{7*V}{35}+ \dfrac{5*V}{35} \\ D_1+D_2= \dfrac{12V}{35} \\ Time \ for \ the \2 \pumps=V=(D_1+D_2)*\dfrac{35}{12}==>2H55min[/tex]

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