Finding the Fourth Proportional to 390,404.30, 538,747.81 and 215,980.94

Step by Step Solution

1. Step 1: Write the proportion equation
   390,404.30 : 538,747.81 = 215,980.94 : x
2. Step 2: Convert to fraction form
   390,404.30/538,747.81 = 215,980.94/x
3. Step 3: Cross multiply
   390,404.30x = 538,747.81 × 215,980.94
4. Step 4: Simplify right side
   390,404.30x = 116,359,256,203.20
5. Step 5: Solve for x
   x = 116,359,256,203.20/390,404.30
6. Step 6: Final answer
   x = 298,048.09