Finding the Fourth Proportional to 428,015.34, 642,086.06 and 128,520.04

Step by Step Solution

1. Step 1: Write the proportion equation
   428,015.34 : 642,086.06 = 128,520.04 : x
2. Step 2: Convert to fraction form
   428,015.34/642,086.06 = 128,520.04/x
3. Step 3: Cross multiply
   428,015.34x = 642,086.06 × 128,520.04
4. Step 4: Simplify right side
   428,015.34x = 82,520,927,719.86
5. Step 5: Solve for x
   x = 82,520,927,719.86/428,015.34
6. Step 6: Final answer
   x = 192,799.00