To find the relative frequency of people who prefer island vacations and also prefer swimming, we need to divide the number of people who prefer both activities by the total number of people who prefer island vacations.
Relative frequency = Number of people who prefer swimming on island / Total number of people who prefer island vacation
Relative frequency = 40 / 12 + 20 + 45 = 40 / 77 ≈ 0.52
Converting this to a percentage gives:
Relative frequency ≈ 0.52 * 100% = 52%
Therefore, the relative frequency of people who prefer island vacations also prefer swimming is approximately 52%.