A tank contains 1000L of brine with 10kg of dissolved salt. Pure water enters the tank at a rate of 25 L/min. The solution is kept thoroughly mixed and drains from the tank at the same rate. How much salt is in the tank after t minutes?

(a) 5000 kilos

Step-by-step explanation:

If  is the amount of salt (in kg) after  minutes, then  and the total amount of liquid in the tank remains constant at 1000 L.

and

Because , we have

so

Since  is continuous, , and the right-hand side is never zero, we deduce that  is always positive.

Thus,  and

(b)

After one hour,

The correct answer is D. to 2π

Step-by-step explanation:

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