A student uses a Geiger-Muller tube to measure the background radiation count rate over four separate one-minute intervals. The results are shown in the table below.
| 1st count rate | 2nd count rate | 3rd count rate | 4th count rate | |
|---|---|---|---|---|
| count rate in cpm | 43 | 47 | 41 | 45 |
Calculate the mean of the four count rate measurements shown in the table.
81 exam-style questions on Edexcel GCSE Physics 6.1 Atomic structure and isotopes, covering 6.1.1 Structure of the atom, 6.1.2 Isotopes: atomic and mass number, 6.1.3 Sub-atomic particles: masses and charges, and 6.1.4 Electron orbits and energy changes. Each one has a worked solution and a mark scheme showing where the marks go.