Finding the Fourth Proportional to 1,403.69, 2,105.87 and 429.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,403.69 : 2,105.87 = 429.72 : x
2. Step 2: Convert to fraction form
   1,403.69/2,105.87 = 429.72/x
3. Step 3: Cross multiply
   1,403.69x = 2,105.87 × 429.72
4. Step 4: Simplify right side
   1,403.69x = 904,932.31
5. Step 5: Solve for x
   x = 904,932.31/1,403.69
6. Step 6: Final answer
   x = 644.68