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?

Arestaurant manager wanted to get a better understanding of the tips her employees earn, so she decided to record the number of patrons her restaurant receives over the course of a week, as well as how many of those patrons left tips of at least 15%. the data she collected is in the table below. day mon tue wed thu fri sat sun patrons 126 106 103 126 153 165 137 tippers 82 87 93 68 91 83 64 which day of the week has the lowest experimental probability of patrons tipping at least 15%? a. sunday b. saturday c. friday d. thursday