Answer:
Electric car = Exponential function (decreasing cost)
Gasoline car = Exponential function (increasing cost)
Step-by-step explanation:
The given data the Electric car, we have;
Time (years) 
Cost (thousands of dollars)
0 35
5 27
10 21
15 16
20 12.5
The difference between successive term is such that each term decreases by approximately the same percentage given as follows
1st and 2nd term (35 - 27)/35 × 100 ≈ 22.8571% decrease
2nd and 3rd term (27 - 21)/27 × 100 ≈ 22.222% decrease
3rd and 4th term (21 - 16)/21 × 100 ≈ 23.81% decrease
4th and 5th term (16 - 12.5)/16 × 100 ≈ 21.875% decrease
Therefore. the electric car is best approximated by exponential function
The given data the Gasoline car, we have;
Time (years) Cost (thousands of dollars)
0 35
5 40.2
10 46.3
15 53.2
20 61.2
The difference between successive term is such that each term increases by approximately the same percentage given as follows
1st and 2nd term (40.2 - 35)/35 × 100 ≈ 14.857% decrease
2nd and 3rd term (46.3 - 40.2)/40.2 × 100 ≈ 15.174% decrease
3rd and 4th term (53.2 - 46.3)/46.3× 100 ≈ 14.9% decrease
4th and 5th term (61.2 - 53.2)/53.2× 100 ≈ 15.03% decrease
Therefore. the Gasoline car is best approximated by exponential function
