What is the cumulative frequency of the interval 10-20 if the frequency is 5?

The cumulative frequency of the interval 10-20, if the frequency is 5, depends on the previous intervals' frequencies.

Cumulative frequency is a running total of frequencies through the intervals in a frequency distribution. To find the cumulative frequency for the interval 10-20, you need to add the frequency of this interval to the cumulative frequency of the previous interval. For example, if the cumulative frequency of the interval before 10-20 (say 0-10) is 7, then the cumulative frequency for 10-20 would be 7 (previous cumulative frequency) + 5 (current interval frequency) = 12.

If there are no previous intervals, meaning 10-20 is the first interval, then the cumulative frequency is simply the frequency of that interval, which is 5. However, in most cases, you will have multiple intervals, and you need to add up all the frequencies from the start up to the interval in question to get the cumulative frequency.

Understanding cumulative frequency helps in analysing data distributions and is particularly useful in creating cumulative frequency graphs, which can show the number of observations below a particular value in a dataset. This can be helpful in identifying medians, quartiles, and other statistical measures.