Finding the Fourth Proportional to 1,128.49, 1,557.41 and 686.39

Step by Step Solution

1. Step 1: Write the proportion equation
   1,128.49 : 1,557.41 = 686.39 : x
2. Step 2: Convert to fraction form
   1,128.49/1,557.41 = 686.39/x
3. Step 3: Cross multiply
   1,128.49x = 1,557.41 × 686.39
4. Step 4: Simplify right side
   1,128.49x = 1,068,979.43
5. Step 5: Solve for x
   x = 1,068,979.43/1,128.49
6. Step 6: Final answer
   x = 947.27