Study text: "Essential Mathematics and Statistics for Science", 2nd Edition,

G Currell & A A Dowman, Wiley-Blackwell, 2009

G Currell & A A Dowman, Wiley-Blackwell, 2009

- A population increases by 50% every
*T*= 10 years.

If the population at the start of the first year is 2000, calculate the population when time,*t*= 40 years.

Check ALL of the following expressions/values that give the correct answer. - A bacterial population increases by 10% every 2 hours.

If the population is*N*_{0}= 1.0×10^{4}cells when time,*t*= 0, calculate the population*N*, when time_{t}*t*= 6 hours.

Check ALL of the following expressions/values that give the correct answer. - The activity of a radioactive isotope falls to
**half of the initial activity**during the**half-life period**,*T*_{1/2}= 8 days.

If the activity is*A*_{0}= 6400 Bq when time,*t*= 0, calculate the activity*A*, when_{t}*t*= 24 days.

Check ALL of the following expressions/values that give the correct answer. - The
**decimal reduction time**,*T*, of a bacterial population is the time it takes to fall to_{D}**one tenth**of its initial value.

A bacterial population falls from an initial value*N*_{0}= 6.2×10^{5}cells to*N*= 6.2×10_{t}^{3}cells after a time*t*= 20 min.

Calculate the decimal reduction time,*T*, for this bacteria._{D}- 4 min
- 5 min
- 10 min
- 40 min

- The activity of a radioactive isotope is
*A*_{0}= 12800 Bq when time,*t*= 0, and falls to activity*A*= 800 Bq when_{t}*t*= 24 days.

Calculate the half life,*T*_{1/2}, of this isotope.- 1.5 days
- 3 days
- 6.0 days
- 12 days

- The activity of a radioactive isotope is
*A*_{0}= 3.0×10^{5}Bq when time,*t*= 0, and falls to activity*A*= 5.6×10_{t}^{4}Bq when*t*= 86.0 days.

Calculate the half life,*T*_{1/2}, of this isotope.- 34.6 days
- 35.5 days
- 36.7 days
- 38.2 days