Arithmetic Mean-Raw Data
- adding together all the values and dividing by the number of items.
Assumed Mean method: Sometimes we can make calculations easy by working from an entry that we guess to be the right answer. This guessed number is called the assumed mean.
In does not matter which number is chosen as the assumed mean; we need a number that would make our calculations simpler. Perhaps a choice of number that is closer to most of the entries would help; it need not even be in the list given.
Correct mean = Assumed Mean + Mean difference
Arithmetic Mean - Ungrouped Frequency Distribution
Ar. Mean-Grouped Frequency Distribution
$Mid\ Value = \frac{UCL + LCL}{2}$
UCL – Upper Class Limit LCL – Lower Class Limit
- Direct Method
- Assumed Mean Method
- Step Deviation Method
Direct Method
Assumed Mean Method
Step Deviation Method
A special Property
Arithmetic Mean