a.
To find: independent and dependent variables and explain it.
a.

Answer to Problem 80E
Independent variable is x and dependent variable is y.
Explanation of Solution
Given:
The table below shows profit y (In thousands of dollars ) of a property maintenances business for each month of 2018 with x= 1 represents January
Month. x | Profit. y |
1 | 25.2 |
2 | 25.6 |
3 | 26.6 |
4 | 28.3 |
5 | 31.5 |
6 | 35.8 |
7 | 32.8 |
8 | 30.1 |
9 | 28.6 |
10 | 26.9 |
11 | 24.5 |
12 | 22.7 |
The independent variable is x and dependent variable is y .
x represents each month of the year 2018 and y represents the profit (In thousands of dollars ) of a property maintenances business.
b.
To find: the domain of each part of
b.

Answer to Problem 80E
Explanation of Solution
Given information:
The mathematical model for the data given in (a) is given by:
The first function has a domain
The second function has a domain
The best method is to graph the data as points and then graph both functions on top of the point. If one function deviates from the points we knew, then those points are not in the domain of that function, and therefore must be in the domain of other function.
The mathematical model can be redefined as:
c.
To find: the value of f(5).
c.

Answer to Problem 80E
f (5)=31.575
Explanation of Solution
Given information:
Calculation:
Since the numbers are represented in 1000’s, the value 31.575 is 31.575×1000=31,575
That is, the total profit in the month of May was 31,575.
d.
To find: the value of f (11).
d.

Answer to Problem 80E
The value of f (11)= 24.630
Explanation of Solution
Given information:
Calculation:
Since the numbers are represented in 1000’s, the value 24.63 is 24.63×1000=24,630
That is , the total profit in the month of November was 24,630.
e.
To compare: the values from the mathematical model and that of actual value.
e.

Answer to Problem 80E
The model fits the data well.
Explanation of Solution
The value of f (5) from the mathematical model is 31.575 and actual data value of f(5) is 31.5
The value of f (11) from the mathematical model is 24.63 and actual data value of f(11) is 24.5
That is, values from mathematical model and actual data values are same.
The model fits the data well.
Chapter 1 Solutions
EP PRECALC.GRAPHING APPR.-WEBASSIGN-1YR
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