Finding the Third Proportional to 258,285 and 387,421.50

Step by Step Solution

1. Step 1: Write the proportion equation
   258,285 : 387,421.50 = 387,421.50 : x
2. Step 2: Convert to fraction form
   258,285/387,421.50 = 387,421.50/x
3. Step 3: Cross multiply
   258,285x = 387,421.50 × 387,421.50
4. Step 4: Simplify right side
   258,285x = 150,095,418,662.25
5. Step 5: Solve for x
   x = 150,095,418,662.25/258,285
6. Step 6: Final answer
   x = 581,123.25