Finding the Third Proportional to 399.94 and 865.69

Step by Step Solution

1. Step 1: Write the proportion equation
   399.94 : 865.69 = 865.69 : x
2. Step 2: Convert to fraction form
   399.94/865.69 = 865.69/x
3. Step 3: Cross multiply
   399.94x = 865.69 × 865.69
4. Step 4: Simplify right side
   399.94x = 749,414.85
5. Step 5: Solve for x
   x = 749,414.85/399.94
6. Step 6: Final answer
   x = 1,873.83