Finding the Fourth Proportional to 390,139.50, 538,436.34 and 220,384.56

Step by Step Solution

1. Step 1: Write the proportion equation
   390,139.50 : 538,436.34 = 220,384.56 : x
2. Step 2: Convert to fraction form
   390,139.50/538,436.34 = 220,384.56/x
3. Step 3: Cross multiply
   390,139.50x = 538,436.34 × 220,384.56
4. Step 4: Simplify right side
   390,139.50x = 118,663,055,878.91
5. Step 5: Solve for x
   x = 118,663,055,878.91/390,139.50
6. Step 6: Final answer
   x = 304,155.45