Finding the Fourth Proportional to 1,005.69, 1,387.83 and 557.55

Step by Step Solution

1. Step 1: Write the proportion equation
   1,005.69 : 1,387.83 = 557.55 : x
2. Step 2: Convert to fraction form
   1,005.69/1,387.83 = 557.55/x
3. Step 3: Cross multiply
   1,005.69x = 1,387.83 × 557.55
4. Step 4: Simplify right side
   1,005.69x = 773,784.62
5. Step 5: Solve for x
   x = 773,784.62/1,005.69
6. Step 6: Final answer
   x = 769.41