Answer:
The estimate of the proportion of oil tankers that had spills is 65/211 = 0.308.
Explanation:
Proportion of oil tankers that had spills.
Number of tankers with spills divided by the total number of tankers.
In this question:
211 tankers
146 did not have spills, so 211 - 146 = 65 had
Proportion:

The estimate of the proportion of oil tankers that had spills is 65/211 = 0.308.