A sealed source shows an activity of (4.0±0.1)kBq at 10:00 h. The half-life of the radionuclide is 18.0 h.
(a) Find the nominal time after 10:00 h when the activity will reach 1.0 kBq.
(b) Taking the stated uncertainty into account, calculate the earliest and latest possible times (relative to 10:00 h) at which the activity may reach 1.0 kBq. Express all answers in hours, rounded to the nearest 0.1 h.
a. (a) Nominal time to reach 1.0 kBq
b. (b) Earliest and latest possible times considering uncertainty