Finding the Fourth Proportional to 1,128.57, 1,557.12 and 686.46

Step by Step Solution

1. Step 1: Write the proportion equation
   1,128.57 : 1,557.12 = 686.46 : x
2. Step 2: Convert to fraction form
   1,128.57/1,557.12 = 686.46/x
3. Step 3: Cross multiply
   1,128.57x = 1,557.12 × 686.46
4. Step 4: Simplify right side
   1,128.57x = 1,068,900.60
5. Step 5: Solve for x
   x = 1,068,900.60/1,128.57
6. Step 6: Final answer
   x = 947.13