for a group frequency distribution mean is 60 if the number of observation in each class interval be doubled new mean will be.
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Answer:
After reading this article you will learn about frequency distribution and class interval.
Data collected from tests and experiments may have little meaning to the investigator until they have been arranged or classified in some systematic way. Therefore, we have to organize the data into classes or groups on the basis of certain characteristics.
Step-by-step explanation:
Steps:
Rules for classifying scores into what is called a frequency distribution may be laid down as follows:
1. Determine the range or gap between the highest and the lowest scores. The highest score in Table 2.5 is 197 and the lowest is 142, so that the range is 55 (i.e. 197-142). The scores in Table 2.5 represent the test performance of 50 college students upon the modified form of the Army Alpha intelligence examination.
2. Then we have to decide about the number of classes. We usually have 6 to 20 classes of equal length. If the number of scores/events is quite large, we usually have 10 to 20 classes. The number of classes when less than 10 is considered only when the number of scores/values is not too large.Here if we take length of class interval as 10 then the number of class interval will be 55/10 = 5.5 or 6 which is less than the desired number of classes. If we take class length of 5 then the number of classes will be 55/5 = 11, which is 1 less than the actual number of classes shown in Table 2.6, namely 12.
An interval of 3 units will yield 19 classes; an interval of 10, 6 classes. An interval of 3 would spread the data out too much, thus losing the benefit of grouping; whereas an interval of 10 would crowd the scores into too coarse categories. Accordingly, an interval of 5 is chosen as best suitable to the data of Table 2.5.
3.The formula can also be used to decide about length of class interval or h, if we know the range of scores and number of classes used in grouping, as
4. Having determined the length of class interval and No. of classes, one must decide where to start the classes. Since for data in Table 2.5, the lowest score is 142, so we might begin with 140 as it is common to let the first class start with a number which is multiple of class interval (h).
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