. Consider a population composed of two age groups, young people and adults. The total population at...

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Consider a population composed of two age groups, young people and adults. The total population at time t is P(t) = Y(t)+ A(t), in which P(t) is the overall population at t, Y(t) is the number of young people, and A(t) is the number of adults. The initial (time t = 0) number of young people is Y(0) and the initial number of adults is A(0). The rate of growth of the young population is ry and the rate of growth of the adult population is rĄ. (a) At time t = 15, what is the share of young people in the total population? That is, what is Y(t)/P(t) when t = 15? Please give a solution in symbols, and take care to explain your work. (b) At time t = 15, what is the rate of growth of the total population? Give your solution in symbols and please explain the steps of your work. (c) Assume that Y(0) = 40 and A(0) = 60. Also, the growth rates are 2 percent for ry and 1.5 percent for ra. Find a numerical solution for the rate of growth of the total population at time t = 15. Please explain. (d) At t = 20, the growth rate of the young age group abruptly falls from ry to ry. The growth rate of adults, however, stays at ra as it was before. Please find the share of the young in the population at time t 25, that is, find Y(25)/P(25). Give your solution in symbols, and take extra care to explain the steps of your work. Consider a population composed of two age groups, young people and adults. The total population at time t is P(t) = Y(t)+ A(t), in which P(t) is the overall population at t, Y(t) is the number of young people, and A(t) is the number of adults. The initial (time t = 0) number of young people is Y(0) and the initial number of adults is A(0). The rate of growth of the young population is ry and the rate of growth of the adult population is rĄ. (a) At time t = 15, what is the share of young people in the total population? That is, what is Y(t)/P(t) when t = 15? Please give a solution in symbols, and take care to explain your work. (b) At time t = 15, what is the rate of growth of the total population? Give your solution in symbols and please explain the steps of your work. (c) Assume that Y(0) = 40 and A(0) = 60. Also, the growth rates are 2 percent for ry and 1.5 percent for ra. Find a numerical solution for the rate of growth of the total population at time t = 15. Please explain. (d) At t = 20, the growth rate of the young age group abruptly falls from ry to ry. The growth rate of adults, however, stays at ra as it was before. Please find the share of the young in the population at time t 25, that is, find Y(25)/P(25). Give your solution in symbols, and take extra care to explain the steps of your work.