Finding the Fourth Proportional to 394,978.78, 545,069.28 and 213,690.78

Step by Step Solution

1. Step 1: Write the proportion equation
   394,978.78 : 545,069.28 = 213,690.78 : x
2. Step 2: Convert to fraction form
   394,978.78/545,069.28 = 213,690.78/x
3. Step 3: Cross multiply
   394,978.78x = 545,069.28 × 213,690.78
4. Step 4: Simplify right side
   394,978.78x = 116,476,279,597.24
5. Step 5: Solve for x
   x = 116,476,279,597.24/394,978.78
6. Step 6: Final answer
   x = 294,892.50