A-level probability question, to bring joy to children at Christmas:… - Sally's Journal — LiveJournal
|Date:||November 19th, 2013 01:50 pm (UTC)|| |
Can't you have a stab at this with expected values?
When you've bought 0 Octonauts, the expected number that you've got that you want is 3.
When you've bought 1, it's 3 + 5/8
When you've bought 2, it's 3 + 5/8 + (4 3/8)/8
When you've bought 3 ... and then your criterion for stopping is something like an expectation value of 7.2. Maybe.