Question 925882
Think of the situation as if concentration and dilution.  The concentration of tags in the population is 280/p  using p for the population.  Next, when deer are taken to check for tags, 45 tagged deer found.  As long as this person or group who took deer to check for tags did not show how many deer were taken to check, the size of the population can not be estimated.  When this unknown number is recorded, then we have a proportion with only p unknown.