Answer:
On day 0 (starting day), the percentage of petri dish occupied by bacteria was 2.44%
Step-by-step explanation:
Rate of growth = 2 (i.e. doubles every day)
Petri dish was filled to 100% on day 12.
Let
P(0) = percentage of Petri dish occupied on day 0, then
equation of percentage a function of time in x days
P(x) = P(0)*r^x ......................(1)
where
100% = P(12) = p(0) * 2^12 = 4096 P(0)
=>
P(0) = 100% / 4096 = 0.0244%
Next, to find percentage on February 14 (Valentine's day!)
Day 0 is February 9, so February 14 is the fifth day, so x=5.
Substitute x=5 in equation (1) above,
P(x) = P(0)*r^x
P(5) = P(0)*2^5
P(5) = 0.0244*2^5 = 0.0244*32 = 0.781%
Ans. the 0.781% of the petri dish was filled with bacteria after 5 days on February 14th.
