Engineering Board Exam Reviewer · Applications: Growth and Decay · medium

A population of bacteria starts at 500 and grows exponentially with k=0.3 per hour. Find the population after 4 hours.

  1. 1660
  2. 2000
  3. 1100
  4. 600

Answer

A. 1660

Solution

P=500e0.3(4)=500e1.2 1660.

More Applications: Growth and Decay questions

  1. A radioactive substance initially has 80 grams and decays to 20 grams after 40 days. Find the decay constant k.
  2. A culture of bacteria grows from 1000 to 4000 in 3 hours. Find the growth constant k.
  3. A population grows according to dP/dt=kP. If the population doubles in 10 years, find k.
  4. A radioactive substance decays according to dA/dt=-kA. If its half-life is 20 years, find k.
  5. A bacteria culture grows exponentially and triples in 5 hours. Find the growth constant k in dP/dt=kP.
  6. A radioactive isotope has a decay constant k=0.05 per year. Find its half-life.
  7. Money is invested at a continuously compounded interest rate of 6% per year (dA/dt=rA). How long will it take for the investment to double?

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