Finding the Third Proportional to 638,128.50 and 987,964.50

Step by Step Solution

1. Step 1: Write the proportion equation
   638,128.50 : 987,964.50 = 987,964.50 : x
2. Step 2: Convert to fraction form
   638,128.50/987,964.50 = 987,964.50/x
3. Step 3: Cross multiply
   638,128.50x = 987,964.50 × 987,964.50
4. Step 4: Simplify right side
   638,128.50x = 976,073,853,260.25
5. Step 5: Solve for x
   x = 976,073,853,260.25/638,128.50
6. Step 6: Final answer
   x = 1,529,588.25