Finding the Third Proportional to 639.69 and 1,017.25

Step by Step Solution

1. Step 1: Write the proportion equation
   639.69 : 1,017.25 = 1,017.25 : x
2. Step 2: Convert to fraction form
   639.69/1,017.25 = 1,017.25/x
3. Step 3: Cross multiply
   639.69x = 1,017.25 × 1,017.25
4. Step 4: Simplify right side
   639.69x = 1,034,789.62
5. Step 5: Solve for x
   x = 1,034,789.62/639.69
6. Step 6: Final answer
   x = 1,617.63