Finding the Fourth Proportional to 1,005.39, 1,387.38 and 557.24

Step by Step Solution

1. Step 1: Write the proportion equation
   1,005.39 : 1,387.38 = 557.24 : x
2. Step 2: Convert to fraction form
   1,005.39/1,387.38 = 557.24/x
3. Step 3: Cross multiply
   1,005.39x = 1,387.38 × 557.24
4. Step 4: Simplify right side
   1,005.39x = 773,096.69
5. Step 5: Solve for x
   x = 773,096.69/1,005.39
6. Step 6: Final answer
   x = 768.95