This histogram shows the percentage of the population that smokes tobacco for 123 countries. Which one of the following values is the most reasonable estimate for the IQR?

9.5

Step-by-step explanation:

The formula for interquartile range = Third Quartile - 1st Quartile

= Q3 - Q1

Looking at the histogram given, the class width = 6

Step 1

We find the number of values = n

n = 1 + 12 + 26 + 27 + 31 + 19 + 6 + 1

= 123

Frequency Cumulative Frequency

1 1

12 13

26 39

27 66

31 97

19 116

6 122

1 123

Step 2

We find Q1 ( First Quartile)

Q1 =1/4 (n + 1) value

Q1 = 1/4(124) value

= 31st value

The first Quartile = 31st value

31 - 13 = 18

31st value = 12 + (18/26 × class width)

= 12 +( 18/26 × 6)

First Quartile = 16.153846154

Third Quartile =Q3 =3/4 (n + 1) value

Q1 = 3/4(124) value

= 93rd value

The first Quartile = 93rd value

93 - 66 = 27

93rd value = 1 + (27/97 × class width)

=24 +( 27/97 × 6)

Third Quartile= 25.670103093

Interquartile range = Q3 - Q1

= 25.670103093 - 16.153846154

= 9.5162569392

Approximately = 9.5

Inter Quartile range = 9.5