Construct a frequency table with equal class intervals from the following data on the monthly wages (in rupees) of 28 labourers working in a factory, taking one of the class intervals as 210-230 (230 not included).

220, 268, 258, 242, 210, 268, 272, 242, 311, 290, 300, 319, 304, 302, 318, 306, 292, 254, 278, 210, 240, 280, 316, 306, 215, 256, 236.

Minimum observation = 210


Maximum observation = 320


The classes of equal size covering the given data are:


210-230, 230-250, 250-270, 270-290, 290-310, and 310-330


So, frequency table will be as given below,


Class



Frequency



210 – 230



4



230 – 250



4



250 – 270



5



270 – 290



3



290 – 310



7



310 – 330



5



8