1. Suppose that the population of a certain country grows at an annual rate of 4%. If the current population is 3 million:

a) What will the population be in 10 years?

b) How long will it take the population to reach 8 million?

2. If the current population is 10 million, and it grows to 25 million after 15 years, calculate the growth rate for this population.

3. The doubling time of a population of flies is eight days. If there are initially 100 flies:

a) How many flies will there be in 17 days?

b) How many flies will there be in two months?

4. Suppose that a bacteria population doubles every six hours. If the initial population is 4000 individuals:

a) Calculate the number of bacteria after two days.

b) How many hours would it take the population to increase to 25,000?

5. The doubling time of a population of bacteria is 6 minutes. If there are initially 40 bacteria:

a) How many bacteria will there be in one hour?

b) How long would it take the population to increase to 1280?

6. If there are currently 5000 elephants left in the world, and it has a half-life of 20 years:

a) How many will remain in 60 years?

b) How long would it take the population to decrease to 156?

7. Plutonium has a half-life of 24,000 years. Suppose that 30 pounds of it was dumped at a nuclear waste site. How long would it take for it to decay into 2 pounds?

Answer :

Final answer:

To calculate population growth using the formula Population = Initial Population * (1 + Growth Rate/100)^N. Population after 10 years is 3,940,000. It would take approximately 17.5701 years for the population to reach 8 million.


Explanation:

To calculate the population growth, we can use the formula:


Population = Initial Population * (1 + Growth Rate/100)^N


1. For the first question, if the current population is 3 million and the annual growth rate is 4%, the population after 10 years would be:



  1. Population = 3,000,000 * (1 + 4/100)^10 = 3,940,000


2. To find out how long it would take for the population to reach 8 million, we can rearrange the formula and solve for N:


8,000,000 = 3,000,000 * (1 + 4/100)^N


Taking the logarithm of both sides, we get:


N = log(8,000,000/3,000,000) / log(1 + 4/100) ∼ 17.5701


Therefore, it would take approximately 17.5701 years for the population to reach 8 million.


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