Question 1199932
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A = person is 100% correct
B = person made a minor error
C = person made a major error


P(A) = 0.25
P(B) = 0.72
P(C) = 0.03


Events A,B,C are mutually exclusive. 
This fact allows us to add the probabilities like so:


P(B or C) = P(B)+P(C)
P(B or C) = 0.72+0.03
P(B or C) = 0.75


Answer: 0.75
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