Finding the Fourth Proportional to 13,609.72, 18,780.61 and 7,641.79

Step by Step Solution

1. Step 1: Write the proportion equation
   13,609.72 : 18,780.61 = 7,641.79 : x
2. Step 2: Convert to fraction form
   13,609.72/18,780.61 = 7,641.79/x
3. Step 3: Cross multiply
   13,609.72x = 18,780.61 × 7,641.79
4. Step 4: Simplify right side
   13,609.72x = 143,517,477.69
5. Step 5: Solve for x
   x = 143,517,477.69/13,609.72
6. Step 6: Final answer
   x = 10,545.22