Finding the Fourth Proportional to 1,128.40, 1,557.03 and 686.35

Step by Step Solution

1. Step 1: Write the proportion equation
   1,128.40 : 1,557.03 = 686.35 : x
2. Step 2: Convert to fraction form
   1,128.40/1,557.03 = 686.35/x
3. Step 3: Cross multiply
   1,128.40x = 1,557.03 × 686.35
4. Step 4: Simplify right side
   1,128.40x = 1,068,667.54
5. Step 5: Solve for x
   x = 1,068,667.54/1,128.40
6. Step 6: Final answer
   x = 947.06