Grouped Data Measures If Spread

Question 1

What happens to the interquartile/percentile/decile ranges if the data is grouped

Answer 1

They can only be estimated

Question 2

How could you estimate the interquartile/percentile/decile ranges

Answer 2

Use linear interpolation

Question 3

How could you use cumulative frequency curves to find interquartile/percentile/decile ranges

Answer 3

Find the percentage in the y axis and draw a line to the frequency curve
Read where it meets the frequency curve