The probability that a flight, provided by airline company "Derry-air" operating on the route Homersville to Springfield, arrives late is p=0.22. If flights are independent, and a sample of 10 flights are taken what is the probability that at most one will arrive late
"At most one will arrive late" means that either:
1) all will arrive on time, or
2) one will be late.
The probability that any one plane arrives on time is 1.00 - 0.22 = 0.78.
1) all ten arriving on time = (0.78)10
2) one will be late but nine arrive on time = 10 x (0.22)1 x (0.78)9
[the factor of 10 is used because the one that arrives late can be
the first plane or the second plane or ... the tenth plane; ten ways]
To get the final answer, calculate the two individual probabilities and add them together.