Which of the following should typically be ignored because spending has already been made and cannot be changed?

Assume the government imposes a $2.25 tax on suppliers, which results in a shift of the supply curve from s1 to s2. the price the seller receives for the product after paying the tax is

Alarge tank is filled to capacity with 500 gallons of pure water. brine containing 2 pounds of salt per gallon is pumped into the tank at a rate of 5 gal/min. the well-mixed solution is pumped out at the same rate. find the number a(t) of pounds of salt in the tank at time t.

Zeta corporation is a manufacturer of sports caps, which require soft fabric. the standards for each cap allow 2.00 yards of soft fabric, at a cost of $2.00 per yard. during the month of january, the company purchased 25,000 yards of soft fabric at $2.10 per yard, to produce 12,000 caps. what is zeta corporation's materials price variance for the month of january?