Answer: 1.5
Explanation:
To find the quartiles, let's first find the median by sorting the data points from least to greatest.
81
,
82
,
83
,
83
84
,
84
,
84
,
85
81,82,83,83⋮84,84,84,8581, comma, 82, comma, 83, comma, start color gray, 83, end color gray, \varvdots, rectangle, start color gray, 84, end color gray, comma, 84, comma, 84, comma, 85
The median is the mean of the two middle numbers.
83
+
84
2
=
167
2
=
83.5
2
83+84
=
2
167
=83.5start fraction, start color gray, 83, end color gray, plus, start color gray, 84, end color gray, divided by, 2, end fraction, equals, start fraction, 167, divided by, 2, end fraction, equals, start color #9d38bd, 83, point, 5, end color #9d38bd
The first quartile is the median of the data points to the left of the median.
81
,
82
,
83
,
83
81,82,83,8381, comma, 82, comma, 83, comma, start color gray, 83, end color gray
Q
1
=
82
+
83
2
=
165
2
=
82.5
Q
1
=
2
82+83
=
2
165
=82.5Q, start subscript, 1, end subscript, equals, start fraction, 82, plus, 83, divided by, 2, end fraction, equals, start fraction, 165, divided by, 2, end fraction, equals, start color #ff00af, 82, point, 5, end color #ff00af
The third quartile is the median of the data points to the right of the median.
84
,
84
,
84
,
85
84,84,84,85start color gray, 84, end color gray, comma, 84, comma, 84, comma, 85
Q
3
=
84
+
84
2
=
168
2
=
84
Q
3
=
2
84+84
=
2
168
=84Q, start subscript, 3, end subscript, equals, start fraction, 84, plus, 84, divided by, 2, end fraction, equals, start fraction, 168, divided by, 2, end fraction, equals, start color #6495ed, 84, end color #6495ed
IQR
=
Q
3
−
Q
1
=
84
−
82.5
=
1.5
IQR
=Q
3
−Q
1
=84−82.5
=1.5