Answer:
Step-by-step explanation:
From the given information:

Given that the solution is pumped at a slower rate of 4gal/min
Then:


The differential equation can be expressed as:

Integrating the linear differential equation; we have::


multiplying above integrating factor fields; we have:

![\dfrac{d}{dt}\bigg [ (50 +t)^2 A \bigg ] = 3 (50 +t)^2](https://tex.z-dn.net/?f=%5Cdfrac%7Bd%7D%7Bdt%7D%5Cbigg%20%5B%20%2850%20%2Bt%29%5E2%20A%20%5Cbigg%20%5D%20%3D%203%20%2850%20%2Bt%29%5E2)

A = (50 + t) + c(50 + t)²
Using the given conditions:
A(0) = 20
⇒ 20 = 50 + c (50)⁻²
-30 = c(50) ⁻²
c = -30 × 2500
c = -75000
A = (50+t) - 75000(50 + t)⁻²
The no. of pounds of salt in the tank after 35 minutes is:
A(35) = (50 + 35) - 75000(50 + 35)⁻²
A(35) = 85 - 
A(35) =69.6193 pounds
A(35)
70 pounds
Thus; the number of pounds of salt in the tank after 35 minutes is 70 pounds.
Correlation coefficient helps us to know how strong is the relation between two variables. The strength of the model is a strong positive correlation.
<h3>What is the correlation coefficient?</h3>
The correlation coefficient helps us to know how strong is the relation between two variables. Its value is always between +1 to -1, where, the numerical value shows how strong is the relation between them and, the '+' or '-' sign shows whether the relationship is positive or negative.
- 1 indicates a strong positive relationship.
- -1 indicates a strong negative relationship.
- A result of zero indicates no relationship at all, therefore, independent variable.
Hence, the strength of the model is a strong positive correlation.
Learn more about Correlation Coefficients:
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A
Because we do what we don
Sean deposits $90 of his $300 paycheck