Problema Solution
10. A bird population is initially 150 and grows at a rate of 6% each year.
a. Find an exponential model of the form P = C ·a
t that models the bird population P, after t years.
b. Find the instantaneous growth rate r, as a percent. Round your answer to 5 decimal places.
c. Write an exponential equation of the form P = Cert for the bird population P after t years.
Answer provided by our tutors
A bird population is initially 150 and grows at a rate of 6% each year.
Since these populations grow exponentially, we are looking for a model of the form
P(t) = C*a^t, t is the time, C and a are the constants that we need to find
a. Find an exponential model that models the bird population P, after t years.
A bird population is initially 150 and grows at a rate of 6% each year.
This means that for t = 0 we have P(0) = 150 thus C*a^0 = C and C = 150
A bird population grows at a rate of 6% each year:
(P(1) - P(0))/P(0) = 0.06
P(1) - P(0) = 0.06*P(0)
150a - 150 = 150*0.06
a = (150*0.06 + 150)/150
a = 1.06
now we can write for the model of the bird population
P(t) = 150*1.06^t
b. Find the instantaneous growth rate r, as a percent. Round your answer to 5 decimal places.
To find the instantaneous growth rate differentiate the expression P(t) = 150*1.06^t
dP(t)/dt = 150*1.06^t*(ln 1.06)
r = 150*1.06^t*(ln 1.06)
r = 8.7403362*1.06^t
c. Write an exponential equation of the form P = Ce^(rt) for the bird population P after t years.
P(t) = Ce^(rt)
P(0) = 150 => C = 150
(P(1) - P(0))/P(0) = 0.06
150(e^r - 1)/150 = 0.06
e^r - 1 = 0.06
r = ln 1.06
r = 0.05827
thus the equation is
P(t) = 150 e^( 0.05827t).