Finding the Fourth Proportional to 1,005.34, 1,387.32 and 557.18

Step by Step Solution

1. Step 1: Write the proportion equation
   1,005.34 : 1,387.32 = 557.18 : x
2. Step 2: Convert to fraction form
   1,005.34/1,387.32 = 557.18/x
3. Step 3: Cross multiply
   1,005.34x = 1,387.32 × 557.18
4. Step 4: Simplify right side
   1,005.34x = 772,986.96
5. Step 5: Solve for x
   x = 772,986.96/1,005.34
6. Step 6: Final answer
   x = 768.88