Given:
The linear function for average test score in your math class is
![f(x)=0.9x+79](https://tex.z-dn.net/?f=f%28x%29%3D0.9x%2B79)
where x is the number of the test taken.
The linear function g(x) in the given table represents the average test score in your science class, where x is the number of the test taken.
To find:
Part A: The test average for your math class after completing test 2.
Part B: The test average for your science class after completing test 2.
Part C: Which class had a higher average after completing test 4?
Solution:
Part A:
We have,
![f(x)=0.9x+79](https://tex.z-dn.net/?f=f%28x%29%3D0.9x%2B79)
Put x=2 in the above function, to find the test average for your math class after completing test 2.
![f(2)=0.9(2)+79](https://tex.z-dn.net/?f=f%282%29%3D0.9%282%29%2B79)
![f(2)=1.8+79](https://tex.z-dn.net/?f=f%282%29%3D1.8%2B79)
![f(2)=80.8](https://tex.z-dn.net/?f=f%282%29%3D80.8)
Therefore, the test average for your math class after completing test 2 is 80.8.
Part B:
From the given table it is clear that g(x) =79 at x=2.
Therefore, the test average for your science class after completing test 2 is 79.
Part C:
Put x=4 in f(x), to find the test average for your math class after completing test 4.
![f(4)=0.9(4)+79](https://tex.z-dn.net/?f=f%284%29%3D0.9%284%29%2B79)
![f(4)=3.6+79](https://tex.z-dn.net/?f=f%284%29%3D3.6%2B79)
![f(4)=82.6](https://tex.z-dn.net/?f=f%284%29%3D82.6)
From the table it is clear that the value of g(x) is increased by 1 as x is increased by 1. So, the value of function g(x) at x=4 must be 1 more than 80.
![g(4)=81](https://tex.z-dn.net/?f=g%284%29%3D81)
It is clear that,
![82.6>81](https://tex.z-dn.net/?f=82.6%3E81)
Therefore, math class had a higher average after completing test 4.