Finding the Fourth Proportional to 1,128.45, 1,557.69 and 686.37

Step by Step Solution

1. Step 1: Write the proportion equation
   1,128.45 : 1,557.69 = 686.37 : x
2. Step 2: Convert to fraction form
   1,128.45/1,557.69 = 686.37/x
3. Step 3: Cross multiply
   1,128.45x = 1,557.69 × 686.37
4. Step 4: Simplify right side
   1,128.45x = 1,069,151.69
5. Step 5: Solve for x
   x = 1,069,151.69/1,128.45
6. Step 6: Final answer
   x = 947.45