Finding the Fourth Proportional to 390,618.56, 538,908.72 and 220,725.92

Step by Step Solution

1. Step 1: Write the proportion equation
   390,618.56 : 538,908.72 = 220,725.92 : x
2. Step 2: Convert to fraction form
   390,618.56/538,908.72 = 220,725.92/x
3. Step 3: Cross multiply
   390,618.56x = 538,908.72 × 220,725.92
4. Step 4: Simplify right side
   390,618.56x = 118,951,123,018.02
5. Step 5: Solve for x
   x = 118,951,123,018.02/390,618.56
6. Step 6: Final answer
   x = 304,519.90