Final answer:
The marginal relative frequency of all the people that like fish is 0.2, or 20%, derived from dividing the number of people who like fish by the total surveyed.
Step-by-step explanation:
The marginal relative frequency of all the people that like fish can be found by dividing the number of people who like fish by the total number of people surveyed. In the example given, the marginal relative frequency is calculated as follows:
Fish = 4/20 = 0.2
So, the marginal relative frequency of people who like fish is 0.2 or 20%. Remember that the sum of all marginal relative frequencies in a distribution must be equal to one. In this case, the sum of 0.4 (for dogs) + 0.4 (for cats) + 0.2 (for fish) equals 1, confirming that the marginal relative frequencies have been calculated correctly.