Finding the Fourth Proportional to 1,131.78, 1,562.31 and 712.74

Step by Step Solution

1. Step 1: Write the proportion equation
   1,131.78 : 1,562.31 = 712.74 : x
2. Step 2: Convert to fraction form
   1,131.78/1,562.31 = 712.74/x
3. Step 3: Cross multiply
   1,131.78x = 1,562.31 × 712.74
4. Step 4: Simplify right side
   1,131.78x = 1,113,520.83
5. Step 5: Solve for x
   x = 1,113,520.83/1,131.78
6. Step 6: Final answer
   x = 983.87