The class marks of a distribution are 26,31,36,41,46,51,56,61,66,71. Find the true class limits.

Explanation

Class size`=`Difference between any two consecutive class marks`=31-26=5`.
Therefore,
Lower limit of first class interval`=26−5/2=23.5`
Upper limit of first class interval`=26+5/2=28.5`
Therefore, first class interval is `23.5-28.5`.
Thus, the class intervals are:
`23.5−28.5`, `28.5−33.5`, `33.5−38.5`, `38.5−43.5`, `43.5−48.5`, `48.5−53.5`.
Since, the classes are formed by exclusive method. Therefore, these limits are true class limits.