An underground military installation is fortified to the extent that it can withstand up to three
direct hits from air-to-surface missiles and still function. Suppose an enemy aircraft is armed
with missiles, each having a 30 % chance of scoring a direct hit.
i. What is the probability that the installation will be destroyed with the seventh missile fired
is obtained by fewer than nine air strikes?
ii. Find the expected air-to-surface missiles strike.