Finding the Fourth Proportional to 20,298.79, 28,009 and 18,665.72

Step by Step Solution

1. Step 1: Write the proportion equation
   20,298.79 : 28,009 = 18,665.72 : x
2. Step 2: Convert to fraction form
   20,298.79/28,009 = 18,665.72/x
3. Step 3: Cross multiply
   20,298.79x = 28,009 × 18,665.72
4. Step 4: Simplify right side
   20,298.79x = 522,808,151.48
5. Step 5: Solve for x
   x = 522,808,151.48/20,298.79
6. Step 6: Final answer
   x = 25,755.63