Answer:
The interquartile range for this data set is 3.
Explanation:
We are given the data set : 3, 4, 4, 6, 7, 7, 9
In order to find the interquartile range, we can create a box plot for this data set. Each box plot contains a minimum, lower quartile, median, higher quartile, and maximum. Let's find the minimum and maximum before the others as it is the easiest one to identify. The minimum here would be 3 since that's the lowest number here in this data set. The maximum here would be 9 since that's the highest number here in this data set. Before we find the lower and higher quartile, let's find the median first since that way, we don't get mixed up between so many numbers. To find the median, you need to find the value that lies at the middle point throughout the data set. Since there are 7 values in this data set which is a odd number, all we need to do is cross out the first and last value as each set goes by.
3, 4, 4, 6, 7, 7, 9
4, 4, 6, 7, 7
4, 6, 7
6
The work above shows each set of the first and last value getting shorter and shorter, so the median of the data set would be 6. The values, 3, 4, and 9 have already been used. Now that we know the median, the second lowest number here is 4 (lower quartile) and the second highest number here is 7 (higher quartile). In order to find the interquartile range, you need to find the difference between the lower quartile and higher quartile, which means to subtract.
7 (higher quartile) and 4 (lower quartile) = 3 (interquartile range)
Therefore, the interquartile range for this data set is 3.