Differential equations:
salt water pours into a full 20 litre tank at a rate of 2 l/min . the inflow initial concentration is 2 kg/l but after 30 minutes the inflow concentration switches to 1 kg/l . the brine in the tank is well mixed and it drains out at a rate of 2 l/min . call y the grams of salt in the tank at time t. the tank is initially full of fresh water. solve the differential equation that models the salt in the tank.
bonus: what is the maximum kg of salt ever in the tank?

a) one student is chosen from classroom a, then a student is chosen from classroom b.  

step-by-step explanation:

independent events are ones in which the probability of one event does not affect the probability of the second event.

one student is chosen from classroom a; this does not affect the chances of choosing a student from classroom b.   this makes these independent events.

when one card is chosen from a standard deck and then set aside before a second card is chosen, the probability of the second card being chosen changes.   this makes them dependent events.

when one student is chosen from classroom a and then a second student is chosen from classroom a, the probability of choosing the second student changes.   this makes them dependent events.

when a letter is chosen from the alphabet and then a second letter is chosen, the probability of choosing the second letter changes.   this makes them dependent events.

pretty sure 750 each month!

step-by-step explanation: