We have the following situation:
• We have a sample of 1453, n = 1453.
• Of these ships, 989 did not have spills.
And from this, we need to estimate the proportion of oil tankers that had spills.
To find it, we can proceed as follows:
1. We need to find the sample proportion of ships that had spills. These ships are:

2. Then the sample proportion is given by:

Therefore, in summary, the proportion of oil tankers that had spills is (as a fraction or decimal with three places):
