Finding the Third Proportional to 393.89 and 839.53

Step by Step Solution

1. Step 1: Write the proportion equation
   393.89 : 839.53 = 839.53 : x
2. Step 2: Convert to fraction form
   393.89/839.53 = 839.53/x
3. Step 3: Cross multiply
   393.89x = 839.53 × 839.53
4. Step 4: Simplify right side
   393.89x = 704,812.72
5. Step 5: Solve for x
   x = 704,812.72/393.89
6. Step 6: Final answer
   x = 1,789.36