The half-life of a radioactive isotope is 6 days. How long will it take for the activity of this isotope to fall from 6400 s^{-1} to 400 s^{-1} ?

4 days

12 days

96 days

24 days

I do not know how to answer this question

Q02

A population grows by 10% every year. If the population, A_{t}, at a time, t years, is given by the equation; A_{t }= A_{o} g^{t} what is the value for g ?

g = 1.1

g = ln(0.1)

g = 0.1

None of the above

I do not know how to answer this question

Q03

An exponential decay of the population, A_{t}, of a bacterial culture can be described at a time t (hours) by the equation: A_{t}= A_{o} (0.27)^{t} The same exponential decay can also be described by the equation: A_{t}= A_{o} e^{-kt} Calculate the value of ‘k’ such that the two equations record the same exponential deacy.

k = 3.70

k = 1.27

k = 0.569

k = 1.31

I do not know how to answer this question

Q04

It is believed that the fraction, F, of a drug remaining in the blood at a time t (in hours) after an injection follows the equation: F = e^{-0.13t} Calculate the time (in hours to 2 dp) taken for the fraction, F, to fall to 0.5?