Finding the Third Proportional to 309.94 and 684.56

Step by Step Solution

1. Step 1: Write the proportion equation
   309.94 : 684.56 = 684.56 : x
2. Step 2: Convert to fraction form
   309.94/684.56 = 684.56/x
3. Step 3: Cross multiply
   309.94x = 684.56 × 684.56
4. Step 4: Simplify right side
   309.94x = 468,625.82
5. Step 5: Solve for x
   x = 468,625.82/309.94
6. Step 6: Final answer
   x = 1,512.00