In statistics, xi represents the ith value of a variable X. It is used to denote the frequency of an event xi, which is the number of times the event occurred in an experiment or study. To find xi, you can use the following steps:
- Find the upper limit of the class.
- Find the lower limit of the class.
- Add the upper and lower limits and divide by 2 to get the class mark, which is designated as xi.
Alternatively, xi can be found using the deviation method of finding the mean. This involves choosing one of the xi values as the assumed mean, denoted by a', and finding the difference di between a and each of the xi values. The deviation of 'a' from each of the xi values is given by di = xi - a. The mean can then be obtained using the formula x = d̅ + a, where d̅ is the average of the di values.
