| Difficulty | Secondary School | High school/other |
| ★ | Basic | Easy |
| ★★ | Demanding | Basic |
| ★★★ | Demanding | |
| ★★★★ | Difficult | |
| ★★★★★ | Very difficult |
How many ionisation events are detected by the Geiger counter in 10 seconds with exactly the same experimental arrangement in 10 years?
Answer: 710 ionization events