Finding the Third Proportional to 478.69 and 814.78

Step by Step Solution

1. Step 1: Write the proportion equation
   478.69 : 814.78 = 814.78 : x
2. Step 2: Convert to fraction form
   478.69/814.78 = 814.78/x
3. Step 3: Cross multiply
   478.69x = 814.78 × 814.78
4. Step 4: Simplify right side
   478.69x = 663,868.49
5. Step 5: Solve for x
   x = 663,868.49/478.69
6. Step 6: Final answer
   x = 1,386.85