Finding the Fourth Proportional to 15,289.75, 21,099.89 and 8,920.72

Step by Step Solution

1. Step 1: Write the proportion equation
   15,289.75 : 21,099.89 = 8,920.72 : x
2. Step 2: Convert to fraction form
   15,289.75/21,099.89 = 8,920.72/x
3. Step 3: Cross multiply
   15,289.75x = 21,099.89 × 8,920.72
4. Step 4: Simplify right side
   15,289.75x = 188,226,210.72
5. Step 5: Solve for x
   x = 188,226,210.72/15,289.75
6. Step 6: Final answer
   x = 12,310.61