Answer
$P(at~least~one)=0.230$
Work Step by Step
The probability that Florida will be hit by at least one major hurricane is the complement of the probability that Florida will not be hit by any major hurricanes.
Using the Complement Rule (see page 275):
$P(at~least~one)=P(x\geq1)=1-P(0)=1-0.770=0.230$
