Answer:
The minimum cost is $17.30c
Step-by-step explanation:
Given
--- Volume
--- cost of wall paint
---cost of ceiling paint
Required
Minimum cost of paint
The volume is calculated as:

Substitute 288 for V

Make z the subject

The surface area is calculated as:

Because xy represent the dimension of the ceiling and the opposite of the ceiling (the floor) will not be painted. Hence, it does not require a coefficient of 2
The cost is:

Substitute 





Differentiate w.r.t x and y


By comparison: 
Set them equal to 0


Substitute x for y


Cross multiply



Take the cube root of both sides
![x = \sqrt[3]{216}](https://tex.z-dn.net/?f=x%20%3D%20%5Csqrt%5B3%5D%7B216%7D)


Substitute 6 for x and for y in 




--- approximated
Answer:
Non-proportional; the rate of change is $40/hour
Step-by-step explanation:
we know that
A relationship between two variables, x, and y, represent a proportional variation if it can be expressed in the form
or
In a proportional relationship the constant of proportionality k is equal to the slope m of the line <u>and the line passes through the origin</u>
Let
x -----> the number of hours
y ----> The total charge in dollars
The equation of the line in slope intercept form is equal to

where
m is the slope
b is the y-intercept
we have

substitute

This relationship is not proportional, because the line not passes through the origin
therefore
Non-proportional; the rate of change is $40/hour
Answer:
A=346.46
Step-by-step explanation:
Using the formulas
A=πr2
d=2r
Solving forA
A=1
4πd2=1
4·π·212≈346.36059
H T
/ / / \ \ \ / / / \ \ \
1 2 3 4 5 6 1 2 3 4 5 6
12 different outcomes
since each side can land with one number
Answer:
24/55
Step-by-step explanation:
6 *4 = 24
11 * 5 = 55
6/11 * 4/5 = 24/55