A microbiologist investigated the efficacy of two different antibiotics against the bacterium Pseudomonas aeruginosa.
During the investigation, the microbiologist:
After 24 hours, they diluted the contents of each flask by 1 in 2 000 0002\,000\,0002000000 (5×10−75 \times 10^{-7}5×10−7). They then transferred 0.15 cm30.15\text{ cm}^30.15 cm3 samples from the first flask onto each of 3 separate nutrient agar plates. They repeated this with 0.15 cm30.15\text{ cm}^30.15 cm3 samples from the second flask and the third flask, resulting in 9 agar plates in total.
They incubated the plates for 48 hours.
Table 1 shows the number of bacterial colonies counted on each plate after incubation:
| Plate | Number of colonies with ciprofloxacin | Number of colonies with tobramycin | Number of colonies with no antibiotic |
|---|---|---|---|
| 1 | 181 | 22 | 340 |
| 2 | 186 | 25 | 344 |
| 3 | 191 | 28 | 351 |
Calculate the mean number of bacteria in the undiluted flask of liquid culture containing ciprofloxacin. Give your answer in standard form.
Starting with a single bacterium, calculate how many generations of binary fission it would take to produce at least the number of bacteria you calculated in part 1 (assume no bacteria die).
