Once, L1 is cleared, you select Edit in Edit menu and enter. Now you type in yout data and enter one by one. It is not easy to construct a frequency table of a data set, unless you are systematic enough. Now on L1 you will see the data is sorted in an increasing order. Now you can count the frequencies.
Problems are at the end.
Some time, it is impossible and unreasonable to try to erect one bar above each data value. In this case, we divide the whole range of data into class intervals. The class frequency of a class interval is the number of data values that fall in the class interval. The table that gives the class intervals and corresponding class frequencies is called class frequency table . We can construct a bar graph by erecting bars above the class intervals, of height equal to the corresponding class frequencies.