Finding the Third Proportional to 397.69 and 864.56

Step by Step Solution

1. Step 1: Write the proportion equation
   397.69 : 864.56 = 864.56 : x
2. Step 2: Convert to fraction form
   397.69/864.56 = 864.56/x
3. Step 3: Cross multiply
   397.69x = 864.56 × 864.56
4. Step 4: Simplify right side
   397.69x = 747,468.32
5. Step 5: Solve for x
   x = 747,468.32/397.69
6. Step 6: Final answer
   x = 1,879.54