Answer:
3.85 hours
Explanation:
We have that the model equation in this case would be of the following type, being "and" the concentration of bacteria:
y = a * e ^ (b * t)
where a and b are constants and t is time.
We know that when the time is 0, we know that there are 100,000 bacteria, therefore:
100000 = a * e ^ (b * 0)
100000 = a * 1
a = 100000
they tell us that when the time is 2 hours, the amount doubles, that is:
200000 = a * e ^ (b * 2)
already knowing that a equals 100,000
e ^ (b * 2) = 2
b * 2 = ln 2
b = (ln 2) / 2
b = 0.3465
Having the value of the constants, we will calculate the value of the time when there are 380000, that is:
380000 = 100000 * (e ^ 0.3465 * t)
3.8 = e ^ 0.3465 * t
ln 3.8 = 0.3465 * t
t = 1.335 / 0.3465
t = 3.85
That is to say that in order to reach this concentration 3.85 hours must pass