Math 116
posted by Carmen .
could someone please evaluate what i have so far and help me with the last few questions...
the linear equation: y = 0.15x + 0.79 represents an estimate of the average cost of gas for year x starting in 1997. the year 1997 would be represented by x = 1, for example, as it is the first year in the study. similarily, 2005 would be year 9, or x=9.
a) what year would be represented by x = 4? 2000
b) what xvalue represents the year 2018? 22
c) what is the slope (or rate of change) of thsi equation?
2018: 0.15(22) + 0.79 = $4.09
1997: $0.94
4.09–0.94 divided by 20181997
= 3.15 divided by 21
= 0.15
= answer is $0.15 per year
d) what is the yintercept? no idea
e) what does the yintercept represent? where the line crosses on the graph
f) assuming this growth trend continues, what will the price of gas be in 2018? how did you arrive at thsi answer?
2018: 0.15(22) + 0.79 = $4.09
1997: 0.15(1) + 0.79 = $0.94
4.09–0.94 divided by 20181997
= 3.15 divided by 21
= 0.15 = $0.15 per year

a, b and c are correct.
d) The yintersept (where x = 0) is y = 0.79
e) The xintercept (where y = 0) is
x = 0.79/0.15 = 5.267
f) $4.09 is correct. Your other calculations are unnecessary