Finding the Third Proportional to 439.50 and 680.50

Step by Step Solution

1. Step 1: Write the proportion equation
   439.50 : 680.50 = 680.50 : x
2. Step 2: Convert to fraction form
   439.50/680.50 = 680.50/x
3. Step 3: Cross multiply
   439.50x = 680.50 × 680.50
4. Step 4: Simplify right side
   439.50x = 463,080.25
5. Step 5: Solve for x
   x = 463,080.25/439.50
6. Step 6: Final answer
   x = 1,053.65