The answer is D u have to multiply the number
Answer:
(a) 
(b) 
Step-by-step explanation:
Given
--- Volume of tank
--- Brine solution
--- Rate in, in gallon/min
--- Rate out, in gallon/min
Required
Determine A(t)
First, calculate the rate in (R in) and (R out) in lb/min



R(out) is calculated by multiply the rate at which brine leaves the tank (lb/gal) * R2
So, we have:



The change in the amount of brin e in the tank at time t is given as:


Rewrite:

Multiply through by dt
![dA = [15 - \frac{A}{100}]* dt](https://tex.z-dn.net/?f=dA%20%3D%20%5B15%20-%20%5Cfrac%7BA%7D%7B100%7D%5D%2A%20dt)
Make dt stand alone


Express as exponents

Multiply through by 100



Apply initial conditions

Substitute 0 for t in: 





Substitute 15 for c in 


Factorize:

How long to empty the tank
Set A to 0

Divide through by 1500

Collect Like Terms

Take ln of both sides



Answer:
The length of segment DA is 15 units
Step-by-step explanation:
- <em>The segment which joining a vertex of a triangle and the midpoint of the opposite side to this vertex is called a median </em>
- <em>The point of intersection of the median of a triangle divides each median into two parts the ratio between them is 1: 2 from the base, which means </em><em>the length of the median is 3 times the part from the base</em><em> </em>
Let us use this rule to solve the question
In Δ AEC
∵ D is the midpoint of EC
∴ AD is a median
∵ B is the midpoint of AC
∴ EB is a median
∵ F is the midpoint of AE
∴ CF is a median
→ The three medians intersected at a point inside the triangle,
let us called it M
∵ AD ∩ EB ∩ CF at M
∴ M is the point of intersection of the medians of Δ AEC
→ By using the rule above
∴ AD = 3 MD
∵ MD = 5
∴ AD = 3(5)
∴ AD = 15 units