HELP?? FAST!! Formula for growth and decay?

Question

There are 2000 bacteria. the population is growing by 40% per hour, but every 3 hours an antibiotic is taken and 80% are immediatly killed. What is the formual to figure out the bacteria BEFORE the Nth dose of antibiotic

the antibiotic is taken immediatly at 2000 bacteria. so only 400 remain. then they grow at 40% per hour fo 3 hours then the antibiotic is taken again....etc

Answer 1

Exponential calculation

e^(rt)

Where r is the rate and t is the time.

Ending amount = beginning amount * e^(rt)
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