Finding the Fourth Proportional to 428,111.55, 641,703.80 and 278,458.79

Step by Step Solution

1. Step 1: Write the proportion equation
   428,111.55 : 641,703.80 = 278,458.79 : x
2. Step 2: Convert to fraction form
   428,111.55/641,703.80 = 278,458.79/x
3. Step 3: Cross multiply
   428,111.55x = 641,703.80 × 278,458.79
4. Step 4: Simplify right side
   428,111.55x = 178,688,061,174.03
5. Step 5: Solve for x
   x = 178,688,061,174.03/428,111.55
6. Step 6: Final answer
   x = 417,386.69