Finding the Fourth Proportional to 428,339.34, 642,484.17 and 128,813.40

Step by Step Solution

1. Step 1: Write the proportion equation
   428,339.34 : 642,484.17 = 128,813.40 : x
2. Step 2: Convert to fraction form
   428,339.34/642,484.17 = 128,813.40/x
3. Step 3: Cross multiply
   428,339.34x = 642,484.17 × 128,813.40
4. Step 4: Simplify right side
   428,339.34x = 82,760,570,383.88
5. Step 5: Solve for x
   x = 82,760,570,383.88/428,339.34
6. Step 6: Final answer
   x = 193,212.63