To find the relative frequency of undecided voters, we first need to determine how many voters were undecided.
Total voters = 5,000
Voters for Candidate A = 1,200
Voters for Candidate B = 3,000
Total voters who expressed a preference (for either candidate) = 1,200 + 3,000 = 4,200
Now, we can find the number of undecided voters:
Undecided voters = Total voters - Voters for Candidate A - Voters for Candidate B
Undecided voters = 5,000 - 4,200 = 800
Next, we calculate the relative frequency of undecided voters:
Relative frequency = (Number of undecided voters) / (Total voters)
Relative frequency = 800 / 5,000 = 0.16
So, the relative frequency of undecided voters is 0.16.