Given 10 strata. 3 blocks in each strata and 3 treatments. Question: what is the probability that the trial will end exactly balanced for 2 of the 3 treatments and with the maximum excess for the other treatment? My solution about which I am unsure. The trial is exactly balanced fro 2 of the 3 treatments and with maximum excess for the other treatment when each stratum is 1/3 through the block. The probability of stopping 1/3 through the block for 10 strata is (1/3)^10. The probability that the first treatment in the block is the same treatment across all strata is also (1/3)^10. There are 3 treatments and each trial could end in favour any of the 3 treatments. So, the probability is 3*(1/3)^10*(1/3)^10. What do you think? Thanks!