Question

A particular strain of bacteria triples in population every 45 minutes. Assuming you start with a 50 bacteria in a petri dish, how many bacteria will there be in 4.5 hours?

Answer 1

Find how long you take

45 minutes=0.75 hours

0.75 times x=4.5
divide both sides by 0.75
x=6

there are six 45 minute sections in 4.5 hours

tripples every time

triples 6 times
times 3 six times
times 3^6

start with 50
50 times 3^6=36450 bacteria

Answer 2

4.5 hours in minutes = 270
Every 45 minutes, bacteria triples
You start with 50
Divide 270 (total time) by 45 (every time bacteria triples)
270/45 = 6
$50 * (3^6)$
$3^6 = 729$
$50 * 729$
36,450 bacteria <span />