Daniel Bernoulli's work in 1760 had the goal of appraising the effectiveness of a controversial inoculation program against smallpox, which at that time was a major threat to public health. His model applies equally well to any other disease that, once contracted and survived, confers a lifetime immunity. Consider the cohort of individuals born in a given year (t = 0), and let n(t) be the number of these individuals surviving t years later. Let x(t) be the number of members of this cohort who have not had smallpox by year t and who are therefore still susceptible. Let 3 be the rate at which susceptibles contract smallpox, and let v be the rate at which people who contract smallpox die from the disease. Finally, let u(t) be the death rate from all causes other than smallpox. Then dx/dt, the rate at which the number of susceptibles declines, is given by d -(3 + μ(t))x. The first term on the right-hand side of this equation is the rate at which susceptibles contract smallpox, and the second term is the rate at which they die from all other causes. Also = -√3x − μµ(t)n, where dn/dt is the death rate of the entire cohort, and the two terms dx dt == dn dt - on the right-hand side are the death rates due to smallpox and to all other causes, respectively. a) Let z = x/n, and show that z satisfies the initial value problem dz dź = −ßz(1 – vz). Observe that this initial value problem does not dt depend on μ(t). b) Find z(t) by solving equation (a).

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Daniel Bernoulli's work in 1760 had the goal of appraising the
effectiveness of a controversial inoculation program against smallpox,
which at that time was a major threat to public health. His model
applies equally well to any other disease that, once contracted and
survived, confers a lifetime immunity. Consider the cohort of
individuals born in a given year (t = 0), and let n(t) be the number of
these individuals surviving t years later. Let x(t) be the number of
members of this cohort who have not had smallpox by year t and who
are therefore still susceptible. Let 3 be the rate at which susceptibles
contract smallpox, and let v be the rate at which people who contract
smallpox die from the disease. Finally, let u(t) be the death rate from
all causes other than smallpox. Then dx/dt, the rate at which the
number of susceptibles declines, is given by d -(3 + μ(t))x. The
first term on the right-hand side of this equation is the rate at which
susceptibles contract smallpox, and the second term is the rate at
which they die from all other causes. Also = -√3x − μµ(t)n, where
dn/dt is the death rate of the entire cohort, and the two terms
dx
dt
==
dn
dt
-
on the right-hand side are the death rates due to smallpox and to all
other causes, respectively.
a) Let z = x/n, and show that z satisfies the initial value problem
dz
dź = −ßz(1 – vz). Observe that this initial value problem does not
dt
depend on μ(t).
b) Find z(t) by solving equation (a).
Transcribed Image Text:Daniel Bernoulli's work in 1760 had the goal of appraising the effectiveness of a controversial inoculation program against smallpox, which at that time was a major threat to public health. His model applies equally well to any other disease that, once contracted and survived, confers a lifetime immunity. Consider the cohort of individuals born in a given year (t = 0), and let n(t) be the number of these individuals surviving t years later. Let x(t) be the number of members of this cohort who have not had smallpox by year t and who are therefore still susceptible. Let 3 be the rate at which susceptibles contract smallpox, and let v be the rate at which people who contract smallpox die from the disease. Finally, let u(t) be the death rate from all causes other than smallpox. Then dx/dt, the rate at which the number of susceptibles declines, is given by d -(3 + μ(t))x. The first term on the right-hand side of this equation is the rate at which susceptibles contract smallpox, and the second term is the rate at which they die from all other causes. Also = -√3x − μµ(t)n, where dn/dt is the death rate of the entire cohort, and the two terms dx dt == dn dt - on the right-hand side are the death rates due to smallpox and to all other causes, respectively. a) Let z = x/n, and show that z satisfies the initial value problem dz dź = −ßz(1 – vz). Observe that this initial value problem does not dt depend on μ(t). b) Find z(t) by solving equation (a).
a) Let z = x/
x/n, and show that z satisfies the initial value problem
-ßz(1 - vz). Observe that this initial value problem does not
dz
=
dt
depend on μ(t).
b) Find z(t) by solving equation (a).
z(t):
= Choose one ▼
c) Bernoulli estimated that v = ß = 1/8. Using these values, determi
the proportion of 69-year-olds who have not had smallpox.
NOTE: Enter an exact answer.
Proportion:
Transcribed Image Text:a) Let z = x/ x/n, and show that z satisfies the initial value problem -ßz(1 - vz). Observe that this initial value problem does not dz = dt depend on μ(t). b) Find z(t) by solving equation (a). z(t): = Choose one ▼ c) Bernoulli estimated that v = ß = 1/8. Using these values, determi the proportion of 69-year-olds who have not had smallpox. NOTE: Enter an exact answer. Proportion:
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