Answer: The amount of salt in the tank after 8 minutes is 36.52 pounds.
Step-by-step explanation:
Salt in the tank is modelled by the Principle of Mass Conservation, which states:
(Salt mass rate per unit time to the tank) - (Salt mass per unit time from the tank) = (Salt accumulation rate of the tank)
Flow is measured as the product of salt concentration and flow. A well stirred mixture means that salt concentrations within tank and in the output mass flow are the same. Inflow salt concentration remains constant. Hence:

By expanding the previous equation:

The tank capacity and capacity rate of change given in gallons and gallons per minute are, respectivelly:

Since there is no accumulation within the tank, expression is simplified to this:

By rearranging the expression, it is noticed the presence of a First-Order Non-Homogeneous Linear Ordinary Differential Equation:
, where
.

The solution of this equation is:

The salt concentration after 8 minutes is:

The instantaneous amount of salt in the tank is:
X is less than -2, so -2 is our largest value of the interval, so it goes on the right. Since there is no lower endpoint (it is ALL values less than -2), we put the negative infinity symbol on the left side. The curved end on -2 indicates an open interval
Answer: y = 8
Step-by-step explanation:
S= number of small boxes
l= number of large boxes
equation 1: s+l=120
equation 2: 15s+45l=3300
solve by elimination, multiply equation 1 by -15.
-15(s+l=120) = -15s-15l=-1800 add to equation 2.
-15s+15s-15l+45l=-1800+3300 = 30l=1500
30l=1500 , l=50
s+l=120, s+50=120 --> s=70
B. 84
The scale factor is 1/12 which means to get back to the actual height, you would multiply 7x12