To calculate the Inter Quartile Range (IQR) of the data set, follow these steps:

1. Sort the data in ascending order: $30, 39, 44, 46, 73, 89, 91, 96, 112, 115$

2. Find the median (Q2): Since there are 10 observations (an even number), the median is the average of the 5th and 6th numbers in the sorted list. $Q2 = \frac{73 + 89}{2} = \frac{162}{2} = 81$

3. Find the first quartile (Q1): Q1 is the median of the first half of the data (the first 5 numbers). $30, 39, 44, 46, 73$ The median of these 5 numbers is the 3rd number: $Q1 = 44$

4. Find the third quartile (Q3): Q3 is the median of the second half of the data (the last 5 numbers). $89, 91, 96, 112, 115$ The median of these 5 numbers is the 3rd number: $Q3 = 96$

5. Calculate the IQR: $IQR = Q3 - Q1 = 96 - 44 = 52$

So, the Inter Quartile Range (IQR) of the data is 52.

Would you like further details or have any questions?

Here are 5 numbered questions for you to ask next:

1. How do you calculate the standard deviation of a data set?
2. Can you explain the difference between variance and standard deviation?
3. How do you find the mode of a data set?
4. What is the difference between a population and a sample in statistics?
5. How do you perform a hypothesis test for the mean of a population?

Tip: The IQR is a measure of statistical dispersion and is useful for identifying the spread of the middle 50% of a data set, often used to detect outliers.