Question

Unit sales for new product ABC have varied in the first seven months of this year as follows:

Month	Jan	Feb	Mar	Apr	May	Jun	Jul
Unit Sales	248	482	341	174	456	310	273

What is the interquartile range (IQR) of the data?

Please specify your answer as an integer.

Note: Use the following formula to find quartile locations:

Lq=(n+1)⋅(q4)Lq=(n+1)⋅(q4)

where q is the quartile index (e.g., q=1 for the first quartile) and n is the number of data points.

Excel's QUARTILE (and PERCENTILE) function uses a different method to compute quartile boundaries.

Answer 1

We have sales for new product ABC in the first seven months of this year, as follows:

MONTH	UNIT SALES	CUMULATIVE FREQUENCY(less than type)
January	248	248
February	482	730
March	341	1071
April	174	1245
May	456	1701
June	310	2011
July	273	2284
Total	2284	-------

The formula for IQR is given by--   

And the formula for q^th quartile can given as--  

Then,

Then,