Finding the Fourth Proportional to 642,388.56, 886,470.12 and 355,920.72

Step by Step Solution

1. Step 1: Write the proportion equation
   642,388.56 : 886,470.12 = 355,920.72 : x
2. Step 2: Convert to fraction form
   642,388.56/886,470.12 = 355,920.72/x
3. Step 3: Cross multiply
   642,388.56x = 886,470.12 × 355,920.72
4. Step 4: Simplify right side
   642,388.56x = 315,513,083,368.89
5. Step 5: Solve for x
   x = 315,513,083,368.89/642,388.56
6. Step 6: Final answer
   x = 491,156.14