Finding the Fourth Proportional to 402,665.72, 555,679.05 and 221,380.74

Step by Step Solution

1. Step 1: Write the proportion equation
   402,665.72 : 555,679.05 = 221,380.74 : x
2. Step 2: Convert to fraction form
   402,665.72/555,679.05 = 221,380.74/x
3. Step 3: Cross multiply
   402,665.72x = 555,679.05 × 221,380.74
4. Step 4: Simplify right side
   402,665.72x = 123,016,636,513.10
5. Step 5: Solve for x
   x = 123,016,636,513.10/402,665.72
6. Step 6: Final answer
   x = 305,505.61