37% traveled by airplane
This means the probability of traveling by airplane (P(A)) is 0.37
8% traveled by train
This means the probability of traveling by train (P(T)) is 0.08
7% traveled by airplane and train
This double counts the people who traveled by both airplane and train.
We need to subtract this 7% from both the airplane and train percentages to get the correct probabilities.
So the corrected probabilities are:
P(A) = 0.37 - 0.07 = 0.30
P(T) = 0.08 - 0.07 = 0.01
Let's verify that these corrected probabilities add up to 1 (100%):
P(A) + P(T) = 0.30 + 0.01 = 0.31
Since the problem states only 37% traveled by airplane and 8% by train, with 7% by both, the remaining 48% must have traveled by other means.
So we can add that to get a total probability of 1:
P(A) + P(T) + P(other) = 0.30 + 0.01 + 0.48 = 0.79
Therefore, the corrected probabilities are:
P(A) = 0.30
P(T) = 0.01
P(other) = 0.48