The formula for the mean using the classmark is as follows:

where:
x = measurement or score
f = frequency
X = classmark
n = total frequency

The steps in computing the mean using the midpoint formula are as follows:
1. Construct the column for the classmark (X). The class mark is the midpoint of the lower and upper limits of a given class interval. The midpoint is founded by getting one-half of the sum of the upper limit and the lower limit.
2. Multiply each classmark by its corresponding frequency. This will be entered in the column for fX.
3. Get the sum of the values obtained in Step 2 to get ∑fx.
4. Substitute the obtained values in Step 3 in the formula to find the mean.

This entry was posted on Monday, July 10th, 2006 at 1:37 am and is filed under 4: Measures of Central Tendency. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.