Finding the Fourth Proportional to 1,128.82, 1,557.59 and 686.87

Step by Step Solution

1. Step 1: Write the proportion equation
   1,128.82 : 1,557.59 = 686.87 : x
2. Step 2: Convert to fraction form
   1,128.82/1,557.59 = 686.87/x
3. Step 3: Cross multiply
   1,128.82x = 1,557.59 × 686.87
4. Step 4: Simplify right side
   1,128.82x = 1,069,861.84
5. Step 5: Solve for x
   x = 1,069,861.84/1,128.82
6. Step 6: Final answer
   x = 947.77