A researcher has decided to create a frequency distribution using the following classes:
30-45, 45-60, 60-75, 76 & over.
The selection of this set involves which of the following?
I. non-overlapping classes.
II. open-ended classes.
III. equal class intervals -
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A. B. C. D. E.E
Note that "76 & over" is an open-ended class. Also, the classes are overlapping (for e.g., the classes "30-45" and "45-60" have the point "45" in common).
The researcher has decided to create a frequency distribution using the classes 30-45, 45-60, 60-75, and 76 & over. Let's analyze each statement and determine which ones apply:
I. Non-overlapping classes: Non-overlapping classes refer to the situation where each data point can only be assigned to one class. In this case, the researcher has defined distinct intervals for each class, such as 30-45, 45-60, 60-75, and 76 & over. These intervals do not overlap with each other, ensuring that each data point falls into only one class. Therefore, statement I is correct.
II. Open-ended classes: Open-ended classes are those that do not have defined upper or lower boundaries. In the given frequency distribution, the class "76 & over" represents an open-ended class because it does not have a specific upper boundary. It includes all values greater than or equal to 76. Therefore, statement II is correct.
III. Equal class intervals: Equal class intervals mean that the width of each class interval is the same. In this case, the researcher has not provided information about the specific width of the intervals. However, based on the given information, it is reasonable to assume that the researcher has used equal class intervals for this frequency distribution. Without further information, we can assume that the width of each interval (e.g., 30-45, 45-60, etc.) is the same. Therefore, statement III is likely correct.
Based on the analysis above, the correct answer is C. I & III only, as both statements I and III apply to the given frequency distribution.