Question

Choose the correct formula of the inter-quartile range:

• A. Lower quartile $-$ Upper quartile
• B. Upper quartile $-$ Lower quartile
• C. Upper quartile $+$ Lower quartile
• D. $2\times$ Median

Answer 1

The correct option is B Upper quartile $-$ Lower quartile

The lower quartile is the median of the data points to the left of the median.

The upper quartile is the median of the data points to the right of the median.

The difference between the upper quartile and the lower quartile of a data set is called as interquartile range.
$\therefore$ Inter-quartile range $=$ Upper quartile $-$ Lower quartile

Example:
Consider the box and whisker plotThe interquartile range of the above data set is $12-7=5.$