To solve this task, we need to develop a cross-tabulation of the given data. We are asked to divide the $x$ values into classes of $10-29$, $30-49$, and so on, while dividing the $y$ values into classes of $40-59$, $60-79$, and so on.

Step-by-Step Process

1. Identify Classes for $x$:

   • 10-29
   • 30-49
   • 50-69
   • 70-89

2. Identify Classes for $y$:

   • 40-59
   • 60-79
   • 80-99

3. Count Observations in Each Class Combination:

Explanation:

• For $x = 10-29$, count how many corresponding $y$ values fall into each of the $y$ ranges.
  • $y = 72, 99, 58, 34, 60, 22, 77, 85, 45, 47, 98, 71, 32, 81, 64, 68, 67, 39, 28$
• We repeat this process for the other $x$-classes and fill in the table.

Would you like more details on any of these steps or have questions? Here are five related questions to expand on this:

1. How do you calculate marginal totals in a cross-tabulation?
2. Can cross-tabulation help in identifying correlations between variables?
3. What is the importance of choosing appropriate class intervals in cross-tabulation?
4. How could you visualize this cross-tabulation using a heatmap?
5. What other data analysis techniques could be applied to this dataset?

Tip: Cross-tabulation is especially useful for categorical data analysis and identifying relationships between two variables at different levels.