Which of the following is not a valid function that can be used with DataFrames ?

1. count()
2. sum()
3. length()
4. mad()

The technique that divides total distribution of data into a given number of equal proportions is called a …………… .

1. quartile
2. tercile
3. median
4. quantile

To divide total distribution of given data in two equal parts, …………… function is used.

1. median()
2. quartile()
3. quantile()
4. all of these

To divide total distribution of given data in four equal parts, …………… function is used.

1. median()
2. quartile()
3. quantile()
4. all of these