Finding the Fourth Proportional to 1,986.49, 2,978.49 and 688.06

Step by Step Solution

1. Step 1: Write the proportion equation
   1,986.49 : 2,978.49 = 688.06 : x
2. Step 2: Convert to fraction form
   1,986.49/2,978.49 = 688.06/x
3. Step 3: Cross multiply
   1,986.49x = 2,978.49 × 688.06
4. Step 4: Simplify right side
   1,986.49x = 2,049,379.83
5. Step 5: Solve for x
   x = 2,049,379.83/1,986.49
6. Step 6: Final answer
   x = 1,031.66