
Lia W.
asked 04/01/21Can someone pls help, I know it’s a lot but I’ve been stuck on this for a while now
The data in the function can be modeled by an exponential function. Find the function that would fit the data.
Year Population
0 31
1 50
2 80
3 130
4 200
After completing the regression using this information the value of a is (__), the value of b is (__). This is an example of exponential (__). The equation for the situation is
f(x)= (__). Use the equation to predict the population for 8 years.
3 Answers By Expert Tutors
Raymond B. answered 04/01/21
Math, microeconomics or criminal justice
P = a(b)^rt where a= 31, r = rate of increase, t = time
31 = a(b)^0 = a
a = 31
50= 31b^r
50b = 31b^2r
80=31b^2r subtract from above
50b-80 = 0
b = 8/5 = 1.6
P = 31(1.6)^rt r= about 1
P= 31(1.6)^t
P= 31(1.6)^8 = about 1331 in 8 years
Lia W.
Thank you!04/01/21

Bradford T. answered 04/01/21
Retired Engineer / Upper level math instructor
Need to fit the data to f(x) = Arx.
First, convert the table to log(y)
Year Population log(Population)
0 31 1.49
1 50 1.7
2 80 1.9
3 130 2.1
4 200 2.3
Doing linear regression to fit the log(data) to a line: y = mx+b
m = 0.202
b = 1.494
r = 10m = 1.59
A = 10b = 31.2
f(x) = 31.2(1.59)x
Checking
year P
0 31.2
1 49,6
2 78.9
3 125.4
4 199.4
f(8) ≈ 31.2(1.59)8 ≈ 1274
Lia W.
Thank you!04/01/21

Yefim S. answered 04/01/21
Math Tutor with Experience
P(t) = P0bt;
t = 0, P(0) = P0= 31; so P(t) = 31bt;
t = 1, P(1) = 31b = 50; so b = 50/31;
P(t) = 31(50/31)t.
Let check how this function works for others years.
t = 2, P(2) = 31(50/31)2 ≈ 80
t = 3, P(3) = 31(50/31)3 ≈ 130
t = 4, P(4) = 31(50/31)4 ≈ 209
This tell you that model you have to change.
Now if t = 8 P(8) = 31(50/31)8 ≈ 1419
Lia W.
Thank you!04/01/21
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William W.
Performing regression manually for an exponential function is tricky. Are you allowed to use a calculator?04/01/21