Finding the Fourth Proportional to 1,128.18, 1,557.38 and 686.22

Step by Step Solution

1. Step 1: Write the proportion equation
   1,128.18 : 1,557.38 = 686.22 : x
2. Step 2: Convert to fraction form
   1,128.18/1,557.38 = 686.22/x
3. Step 3: Cross multiply
   1,128.18x = 1,557.38 × 686.22
4. Step 4: Simplify right side
   1,128.18x = 1,068,705.30
5. Step 5: Solve for x
   x = 1,068,705.30/1,128.18
6. Step 6: Final answer
   x = 947.28