Finding the Third Proportional to 619.31 and 685.69

Step by Step Solution

1. Step 1: Write the proportion equation
   619.31 : 685.69 = 685.69 : x
2. Step 2: Convert to fraction form
   619.31/685.69 = 685.69/x
3. Step 3: Cross multiply
   619.31x = 685.69 × 685.69
4. Step 4: Simplify right side
   619.31x = 470,167.35
5. Step 5: Solve for x
   x = 470,167.35/619.31
6. Step 6: Final answer
   x = 759.18