Answer:
IQR = 274
Step-by-step explanation:
Given the unit sales for the months as:
148, 329, 491, 167, 228, 285, 441
Let's rearrange in ascending the values in ascending order (from lowest to highest), we have:
148, 167, 228, 285, 329, 441, 491
Here the total number of data, n is 7
Let's find the quartile locations using the formula:
[tex] Lq = (n + 1) * (\frac{q}{4}) [/tex]
where q is quartile index.
For first quartile, Q1:
[tex] Lq = (7 + 1) * (\frac{1}{4}) [/tex]
[tex] Lq = 8 * (\frac{1}{4}) = 2 [/tex]
Thus, the 2nd observation in the data is 167.
Q1 = 167
For third quartile, Q3:
[tex] Lq = (7 + 1) * (\frac{3}{4}) [/tex]
[tex] Lq = 8 * (\frac{3}{4}) = 6 [/tex]
Thus, the 6th observation in the data is 441.
Q3 = 441
The interquartile range, IQR will be:
Q3 - Q1
= 441 - 167
= 274
IQR = 274