Finding the Third Proportional to 386,606 and 578,109

Step by Step Solution

1. Step 1: Write the proportion equation
   386,606 : 578,109 = 578,109 : x
2. Step 2: Convert to fraction form
   386,606/578,109 = 578,109/x
3. Step 3: Cross multiply
   386,606x = 578,109 × 578,109
4. Step 4: Simplify right side
   386,606x = 334,210,015,881
5. Step 5: Solve for x
   x = 334,210,015,881/386,606
6. Step 6: Final answer
   x = 864,471.88