Finding the Third Proportional to 206,405 and 290,663.50

Step by Step Solution

1. Step 1: Write the proportion equation
   206,405 : 290,663.50 = 290,663.50 : x
2. Step 2: Convert to fraction form
   206,405/290,663.50 = 290,663.50/x
3. Step 3: Cross multiply
   206,405x = 290,663.50 × 290,663.50
4. Step 4: Simplify right side
   206,405x = 84,485,270,232.25
5. Step 5: Solve for x
   x = 84,485,270,232.25/206,405
6. Step 6: Final answer
   x = 409,317.94