Using a mark-recapture design, you aim to estimate the size of a rodent population. On the first sampling occasion, you catch and mark 180 individuals. On the second sampling occasion, you again capture rodents and find that 40% of the individuals caught on this occasion were marked. Unfortunately, when the time comes to analyze the data, you find that some data sheets have been misplaced and you don't know the exact number of individuals that were caught on the second occasion. Assuming that there were no births, no deaths, no immigration, and no emigration between the two sampling occasions, your best estimate of the size of the population is: [easy-medium] 72 450 Without knowledge of the sample size on the second occasion, it is impossible to provide a good estimate. 180