Answer:
In the first 3.5 hours, the family travelled 175 miles.
Explanation:
We have the table:
time (hours) distance ( miles)
0 0
1 50
2 100
3 150
4 200
5 250
6 300
7 350
8 400
9 450
This seems like a linear relationship, let's write the general line:
y = a*x + b
That represents this situation, y is the distance in miles and x is the time in hours.
In the line equation, a represents the slope and b the y-intercept.
And if the line passes through the points (x₁, y₁) and (x₂, y₂), then the slope of the line is:
a = (y₂ - y₁)/(x₂ - x₁)
In this case we have a lot of points for the line, we can use any pair we want (we actually should use a few different pairs to see that the slope is always the same)
So if we use the first two (0, 0) and (1, 50)
the slope is:
a = (50 - 0)/(1 - 0) = 50
Now, if we use the third and fifth points (4, 200) and (5, 250) now the slope is:
a = (250 - 200)/(5 - 4) = 50/1 = 50
So we can conclude that the slope of the equation is a = 50
Then the equation is something like:
y = 50*x + b
To find the value of b, we can use any of the points of the line, for example (0, 0)
This means that when x = 0, y also must be 0, then:
0 = 50*0 + b
0 = b
Then the equation is:
y = 50*x
Now, to answer how many miles the family travelled in the first 3.5 hours, we just need to replace x by 3.5 in the equation:
y = 50*3.5 = 175
In the first 3.5 hours, the family travelled 175 miles.