Finding the Third Proportional to 639.56 and 1,018.69

Step by Step Solution

1. Step 1: Write the proportion equation
   639.56 : 1,018.69 = 1,018.69 : x
2. Step 2: Convert to fraction form
   639.56/1,018.69 = 1,018.69/x
3. Step 3: Cross multiply
   639.56x = 1,018.69 × 1,018.69
4. Step 4: Simplify right side
   639.56x = 1,037,724.22
5. Step 5: Solve for x
   x = 1,037,724.22/639.56
6. Step 6: Final answer
   x = 1,622.55