Finding the Fourth Proportional to 20,665.89, 30,780.09 and 20,565.18

Step by Step Solution

1. Step 1: Write the proportion equation
   20,665.89 : 30,780.09 = 20,565.18 : x
2. Step 2: Convert to fraction form
   20,665.89/30,780.09 = 20,565.18/x
3. Step 3: Cross multiply
   20,665.89x = 30,780.09 × 20,565.18
4. Step 4: Simplify right side
   20,665.89x = 632,998,091.27
5. Step 5: Solve for x
   x = 632,998,091.27/20,665.89
6. Step 6: Final answer
   x = 30,630.09