Question

O cada are capacitatea de 120 litri si este alimentata de doua robinete. Functionand separat,primul robinet poate umple cada in 20 de minute, iar al doilea in 30 de minute. In cat timp se va umple cada ,daca vor functiona in acelasi timp ,ambele robinete?

dau coroana!

Answer 1

Primul robinet are debitul x

20 min...................................120 l

1 min .......................................x

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x=6 l / min

Al doilea robinet are debitul y

30 min...................................120 l

1 min.......................................y

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y=4 l / min

Functionand impreuna, in fiecare minut vor curge x+y=10 l.

Timpul de umplere va fi t

1 min...................................10 l

t min ..................................120 l

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t=120 /10

t=10 (min)