To get the probability that randomly selected airfare between Boston and San Francisco will be more than $450, we proceed as follows:
the z-score is given by:
z=(x-μ)/σ
thus the z-score for our information will be:
z=(450-387.20)/68.50
z=0.9168
hence our probability will be:
P(X>x)=1-P(z)
P(z)=0.8212
thus
P(X>x)=1-0.8212=0.1788~17.88%
