Finding the Fourth Proportional to 1,128.74, 1,557.15 and 686.54

Step by Step Solution

1. Step 1: Write the proportion equation
   1,128.74 : 1,557.15 = 686.54 : x
2. Step 2: Convert to fraction form
   1,128.74/1,557.15 = 686.54/x
3. Step 3: Cross multiply
   1,128.74x = 1,557.15 × 686.54
4. Step 4: Simplify right side
   1,128.74x = 1,069,045.76
5. Step 5: Solve for x
   x = 1,069,045.76/1,128.74
6. Step 6: Final answer
   x = 947.11