Finding the Third Proportional to 258,687 and 386,437.50

Step by Step Solution

1. Step 1: Write the proportion equation
   258,687 : 386,437.50 = 386,437.50 : x
2. Step 2: Convert to fraction form
   258,687/386,437.50 = 386,437.50/x
3. Step 3: Cross multiply
   258,687x = 386,437.50 × 386,437.50
4. Step 4: Simplify right side
   258,687x = 149,333,941,406.25
5. Step 5: Solve for x
   x = 149,333,941,406.25/258,687
6. Step 6: Final answer
   x = 577,276.56