Count Rate Is Decays per Time

Start with a fixed detector window: 24 counted decays over 6 seconds. The ledger divides counts by time to get 4 decays per second, but that exact number belongs only to the stated window; real count rates need background subtraction, detector efficiency, dead-time checks, and counting uncertainty.

A count rate is observed decays divided by the time window. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

24 decays over 6 seconds gives a rate of 4 per second.

24\div6=4\ 1/\mathrm{s}

This is a counted window, not a decay fit

The lesson does not infer a decay constant; it only checks the 24-count window.

\mathrm{rate}=4\ 1/\mathrm{s}