Problem 118f

Given information

engineering conferences were announced. Four conferences lasted two days. Thirty-six lasted three days. Eighteen lasted four days. Nineteen lasted five days. Four lasted six days. One lasted seven days. One lasted eight days. One lasted nine days.

And  the length (in days) of an engineering conference.

Step-by-step explanation

The middle value lies between first quartile and third quartile.

The middle is also known as interquartile range. 

Interquartile range is a measure of dispersion. It is defined as the difference between and percentile. And percentile is the first quartile and percentile is the third quartile.