Finding the Fourth Proportional to 402,978.18, 556,087.92 and 221,660.84

Step by Step Solution

1. Step 1: Write the proportion equation
   402,978.18 : 556,087.92 = 221,660.84 : x
2. Step 2: Convert to fraction form
   402,978.18/556,087.92 = 221,660.84/x
3. Step 3: Cross multiply
   402,978.18x = 556,087.92 × 221,660.84
4. Step 4: Simplify right side
   402,978.18x = 123,262,912,680.61
5. Step 5: Solve for x
   x = 123,262,912,680.61/402,978.18
6. Step 6: Final answer
   x = 305,879.87