Answer:
Step-by-step explanation:
This is a differential equation problem most easily solved with an exponential decay equation of the form
. We know that the initial amount of salt in the tank is 28 pounds, so
C = 28. Now we just need to find k.
The concentration of salt changes as the pure water flows in and the salt water flows out. So the change in concentration, where y is the concentration of salt in the tank, is
. Thus, the change in the concentration of salt is found in
inflow of salt - outflow of salt
Pure water, what is flowing into the tank, has no salt in it at all; and since we don't know how much salt is leaving (our unknown, basically), the outflow at 3 gal/min is 3 times the amount of salt leaving out of the 400 gallons of salt water at time t:

Therefore,
or just
and in terms of time,

Thus, our equation is
and filling in 16 for the number of minutes in t:
y = 24.834 pounds of salt
It is A. Because .8 is the same has saying .80, it is .80>.79, and 80 is greater than 79
H = 30.25 hours
c = 15(30.25) = 453.75
c = 453.75 + 245
c = 698.75
Answer: x=2/3
Step-by-step explanation:
Here
we can see that the problem gives us the length of a sandwich of x =
1.2. The problem also asks us for the expression that better
represents the approximate length of the crust given among the
options above. Here we simply have to substitute x to each of the
choices.
The
answer is B) x = 8x² + 34; 45.52 centemiters
I
hope it helps, Regards.