a)He can save, miss, mis
or miss, save, misss
or miss, miss, save
The probability of each is 1/3x2/3x2/3=6/27
Therefore total=3x6/27=18/27=2/3
b)If he fails to save one, then he misses them all ie 2/3x2/3x2/3=8/27
c) he can save, save, miss
or save, miss, save
or miss, save, save
the probability of each is 2/3x1/3x1/3=2/27
therefore total is 3x2/27=6/27=2/9
As for the line and plane thing, if you post questions here I will anser them, If you really want me to summarize the topic tell me first, is this a level or igcse. I think you might be in the wrong board.