Okay so basically you will need two sets of working out.
Sandra:
I=PRN
=14000x7x0.045
=4410
Cindy:
I=PRN
=14000x7x0.06
=5880
5880-4410
=1470
Therefore, Cindy earnt $1470 more than Sandra after 7 years.
Ask a teacher? :)!!!!!!!!!!!!
Answer:

General Formulas and Concepts:
<u>Pre-Algebra</u>
Order of Operations: BPEMDAS
- Brackets
- Parenthesis
- Exponents
- Multiplication
- Division
- Addition
- Subtraction
Equality Properties
<u>Calculus</u>
Derivatives
Basic Power Rule:
- f(x) = cxⁿ
- f’(x) = c·nxⁿ⁻¹
Taking Derivatives with respect to time
Step-by-step explanation:
<u>Step 1: Define</u>
Given:
<u />
<u />
<u />
<u />
<u />
<u />
<u />
<u>Step 2: Solve for </u><em><u>r</u></em>
- Substitute:

- Isolate <em>r</em> term:

- Isolate <em>r</em>:
![\sqrt[3]{\frac{77}{\frac{4}{3} \pi}} = r](https://tex.z-dn.net/?f=%5Csqrt%5B3%5D%7B%5Cfrac%7B77%7D%7B%5Cfrac%7B4%7D%7B3%7D%20%5Cpi%7D%7D%20%20%3D%20r)
- Evaluate:

- Rewrite:

<u>Step 3: Differentiate</u>
<em>Differentiate the Volume Formula with respect to time t.</em>
- Define:

- Differentiate [Basic Power Rule]:

- Simplify:

<u>Step 4: Find radius rate</u>
- Substitute in variables:

- Isolate dr/dt rate:

- Evaluate:

- Rewrite:

- Round:

Our radius is decreasing at a rate of -1.325 cm per second.
4(3)-6(-2)
12- -12
12+12
24