Finding the Third Proportional to 139.31 and 328.69

Step by Step Solution

1. Step 1: Write the proportion equation
   139.31 : 328.69 = 328.69 : x
2. Step 2: Convert to fraction form
   139.31/328.69 = 328.69/x
3. Step 3: Cross multiply
   139.31x = 328.69 × 328.69
4. Step 4: Simplify right side
   139.31x = 108,035.47
5. Step 5: Solve for x
   x = 108,035.47/139.31
6. Step 6: Final answer
   x = 775.49