Final answer:
Swimmers' race completion times are measured on a ratio scale because they can be ordered, differences and ratios are meaningful, and there is a true zero point. Months of the year are measured on an ordinal scale because while they can be ordered, the differences between them are not meaningful and there's no true zero.
Step-by-step explanation:
When discussing different types of measurement scales such as nominal, ordinal, interval, or ratio, we are referring to how data in various forms can be categorized, ordered, and quantified.
For the times for swimmers to complete a 50-meter race, we are looking at data that can be ordered from the fastest to the slowest time and has a true zero point (a time of 0 would mean the swim did not occur). Differences and ratios between the times are meaningful and can be calculated. Therefore, this type of data uses a ratio scale.
Conversely, the months of the year represent an ordinal scale because they can be put in an order (January to December), but the differences between them are not meaningful in terms of magnitude, and there is no true zero month.