Finding the Third Proportional to 1,078.31 and 1,689.61

Step by Step Solution

1. Step 1: Write the proportion equation
   1,078.31 : 1,689.61 = 1,689.61 : x
2. Step 2: Convert to fraction form
   1,078.31/1,689.61 = 1,689.61/x
3. Step 3: Cross multiply
   1,078.31x = 1,689.61 × 1,689.61
4. Step 4: Simplify right side
   1,078.31x = 2,854,779.84
5. Step 5: Solve for x
   x = 2,854,779.84/1,078.31
6. Step 6: Final answer
   x = 2,647.45