Finding the Fourth Proportional to 1,659.98, 2,488.35 and 686.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,659.98 : 2,488.35 = 686.78 : x
2. Step 2: Convert to fraction form
   1,659.98/2,488.35 = 686.78/x
3. Step 3: Cross multiply
   1,659.98x = 2,488.35 × 686.78
4. Step 4: Simplify right side
   1,659.98x = 1,708,949.01
5. Step 5: Solve for x
   x = 1,708,949.01/1,659.98
6. Step 6: Final answer
   x = 1,029.50