The difference between the highest and lowest values of the observations is called

Thirty children were asked about the number of hours they watched T.V. programmes in the previous week. The results were found as follows:

1 6 2 3 5 12 5 8 4 8

10 3 4 12 2 8 15 1 17 6

3 2 8 5 9 6 8 7 14 12

(i) Make a grouped frequency distribution table for this data, taking class width 5 and one of the class intervals as 5-10.

(ii) How many children watched television for 15 or more hours a week?

Tally marks are used to find

The difference between the upper and the lower class limits is called

In the class intervals 10-20, 20-30, 20 is taken in