A student uses a scintillation counter to measure the cumulative background radiation count in a laboratory.
The student records the cumulative count at various times over a 200-second period. They plot the readings and draw a straight line of best fit.
| Time in s | Cumulative count |
|---|---|
| 0 | 0 |
| 35 | 152 |
| 71 | 310 |
| 104 | 445 |
| 143 | 612 |
| 200 | 760 |
Calculate the average count rate, in counts/s, using the line of best fit.