Finding the Fourth Proportional to 1,128.68, 1,557.32 and 686.71

Step by Step Solution

1. Step 1: Write the proportion equation
   1,128.68 : 1,557.32 = 686.71 : x
2. Step 2: Convert to fraction form
   1,128.68/1,557.32 = 686.71/x
3. Step 3: Cross multiply
   1,128.68x = 1,557.32 × 686.71
4. Step 4: Simplify right side
   1,128.68x = 1,069,427.22
5. Step 5: Solve for x
   x = 1,069,427.22/1,128.68
6. Step 6: Final answer
   x = 947.50