Finding the Fourth Proportional to 1,128.87, 1,558.01 and 686.61

Step by Step Solution

1. Step 1: Write the proportion equation
   1,128.87 : 1,558.01 = 686.61 : x
2. Step 2: Convert to fraction form
   1,128.87/1,558.01 = 686.61/x
3. Step 3: Cross multiply
   1,128.87x = 1,558.01 × 686.61
4. Step 4: Simplify right side
   1,128.87x = 1,069,746.96
5. Step 5: Solve for x
   x = 1,069,746.96/1,128.87
6. Step 6: Final answer
   x = 947.63