Finding the Fourth Proportional to 499,857, 690,118.56 and 308,978.88

Step by Step Solution

1. Step 1: Write the proportion equation
   499,857 : 690,118.56 = 308,978.88 : x
2. Step 2: Convert to fraction form
   499,857/690,118.56 = 308,978.88/x
3. Step 3: Cross multiply
   499,857x = 690,118.56 × 308,978.88
4. Step 4: Simplify right side
   499,857x = 213,232,059,736.01
5. Step 5: Solve for x
   x = 213,232,059,736.01/499,857
6. Step 6: Final answer
   x = 426,586.12