Construct a frequency table for the following ages (in years) of 30 students using equal class intervals, one of them being 9-12, where 12 is not included.
18, 12, 7, 6, 11, 15, 21, 9, 8, 13, 15, 17, 22, 19, 14, 21, 23, 8, 12, 17, 15, 6, 18, 23, 22, 16, 9, 21, 11, 16.

Find the mode of the following data: 12, 14, 12, 16, 15, 13, 14, 18, 19, 12, 14, 15, 16, 15, 16, 16, 15,17, 13, 16, 16, 15, 15, 13, 15, 17, 15, 14, 15, 13, 15, 14

Find the median of : 25, 18, 13, 20, 16, 9, 22, 8, 6, 15, 21, 11, 17

15 12 17 10 ? 8 21 6

Construct a frequency distribution for the following series of numbers.2, 3, 4, 6, 7, 8, 9, 9, 11, 12, 12, 13, 13, 13, 14, 14, 14, 15, 16, 17, 18, 18, 19, 20, 20, 21, 22, 24, 24, 25.

Find the median of (i) 7, 11, 25, 45, 23, 12, 11, 9, 10 (ii) 15, 14, 11, 9, 7, 12, 18, 20 (iii) 8, 7, 9, 12, 8, 17, 15, 10 (iv) 14, 18, 12, 9, 3, 5, 11, 11, 19, 2

Form a grouped frequency distribution from the following data by inclusive method taking 4 as the class size of class intervals. 31, 23, 19, 29, 22, 20, 16, 10, 13, 34, 38, 33, 28, 21, 15, 18, 36, 24, 18, 15, 12, 30, 27, 23, 20, 17, 14, 32, 26, 25, 18, 29, 24, 19, 16, 11, 22, 15, 17,10

The range of the data 25, 18, 20, 22, 16, 6, 17, 15, 12, 30, 32, 10, 19, 8, 11 and 20 is

Find the median of : 16, 9, 11, 23, 7, 5, 12, 14, 8, 10, 21