Question

Liz's math test included a survey question asking how many hours students spent studying for the test. The scatter plot below shows the relationship between how many hours students spent studying and their score on the test. A line was fit to the data to model the relationship.
Which of these linear equations best describes the given model?

(Choice A)
y=10x+20

(Choice B)
y=20x+20

(Choice C)
y=-20x+20

Based on this equation, estimate the score for a student that spent 3.8 hours studying.

Answer 1

The best equation that best fits the graph is y=20x+20(Choice B). 
The estimate score for a student that spent 3.8 hours studying is about 96.

Hope this helps ;)

Answer 2

THE LINEAR EQUATION
To determine the equation of the line, we should determine the slope of the line first. Here's the following formula to find the slope
m = $\dfrac{y_{2}-y_{1}}{x_{2}-x_{1}}$

The line passes through points
(x₁,y₁) = (0,20)
(x₂,y₂) = (3,80)
Therefore, the slope is
m = $\dfrac{y_{2}-y_{1}}{x_{2}-x_{1}}$
m = $\dfrac{80-20}{3-0}$
m = $\dfrac{60}{3}$
m = 20

Determine the line equation
y - y₁ = m(x - x₁)
y - 20 = 20(x - 0)
y - 20 = 20x
y = 20x + 20

The linear equations best describes the given model is choice B

SCORE FOR 3.8 HOURS STUDYING
To find the score, substitute 3.8 into the coefficient x of the linear equation
y = 20x + 20
y = 20(3.8) + 20
y = 76 + 20
y = 96
The score is 96