Question

What is the IQR of 15,19,20,25,25,28,29,30,30,35,37,43​

Answer 1

Answer:

IQR = 10.

Step-by-step explanation:

15,19,20,25,25,28,29,30,30,35,37,43

There are 12 numbers in the list so the median is the mean of 28 and 29,

The lower quartile is the mean of the  3rd and 4th numbers and the upper quartile is the mean of the  9th and 10th numbers.

Lower quartile = (20+25) / 2 = 22.5.

Upper quartile = (30 + 35) / 2 = 32.5.

So the IQR = 32.5 - 22.5 = 10.

Answer 2

Answer:

IQR = 10

Step-by-step explanation:

The interquartile range is the difference between the upper quartile and the lower quartile.

Firstly find the median of the data set.

The median is the middle value of the data arranged in ascending order. If there is no exact middle then it is the average of the 2 values either side of the middle.

15  19  20  25  25  28  29  30  30  35  37  43

                                   ↑median

median = $\frac{28+29}{2}$ = 28.5

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

15  19  20  25  25  28

               ↑ lower quartile

lower quartile = $\frac{20+25}{2}$ = 22.5

The upper quartile is the middle of the data to the right of the median  

29  30  30  35  37  43

                 ↑ upper quartile

upper quartile = $\frac{30+35}{2}$ = 32.5

IQR = 32.5 - 22.5 = 10