The two mice each eat one-third of a piece of radioactive cheese, leaving one-third behind. Forty minutes later the two mice are caught and eaten by an owl. 6 hours after this meal the owl is caught and has a net body count of 200 counts per minute, which by coincidence, is similar as the remaining piece of the cheese at the similar time? The effective half-life for the radioactive isotope in an owl is 4.00 h and in a mouse 1 h and 20 min.

i) Determine the biological half-life for this isotope in a mouse?

ii) Find out the initial count-rate for the whole piece of cheese?