Finding the Fourth Proportional to 1,128.11, 1,557.27 and 686.16

Step by Step Solution

1. Step 1: Write the proportion equation
   1,128.11 : 1,557.27 = 686.16 : x
2. Step 2: Convert to fraction form
   1,128.11/1,557.27 = 686.16/x
3. Step 3: Cross multiply
   1,128.11x = 1,557.27 × 686.16
4. Step 4: Simplify right side
   1,128.11x = 1,068,536.38
5. Step 5: Solve for x
   x = 1,068,536.38/1,128.11
6. Step 6: Final answer
   x = 947.20