The probability that the Islanders will win exactly zero out of seven games in a series against the Rangers is 0.00048828125. This can be calculated by raising the probability of losing a single game (0.8) to the power of the number of games in the series (7), which gives us 0.8^7 = 0.00048828125. This means that there is a very small chance that the Islanders will win zero games in a seven-game series against the Rangers, given the probability that they will win a single game.