Final answer:
The correct type of scale for measuring annual sales is a ratio scale due to its ability to show meaningful differences, possess an absolute zero, and allow for the calculation of ratios.
Step-by-step explanation:
The type of scale that should be used to measure annual sales in a study comparing sales among different types of customers is a ratio scale. This is because the annual sales figures offer the most detailed level of measurement, providing meaningful differences, an absolute zero point (meaning no sales), and the ability to calculate ratios. For instance, if two customers have annual sales of $100,000 and $200,000, respectively, it can be rightly said that the latter's sales are double the former's. This would not be meaningful on an interval, ordinal, or nominal scale.
An example of nominal scale data could include classifying customers by the type of industry they're in, such as technology, retail, or healthcare, as these categories can't be ordered or used in mathematical calculations. An ordinal scale example might be ranking customer satisfaction on a scale from 'very satisfied' to 'not satisfied', as these have a definite order. For interval scales, an example could be the temperatures at which different operations occur within the company – there is an order and measurable differences, but no true zero point unlike in ratio scales.