Finding the Third Proportional to 638,139.50 and 987,980

Step by Step Solution

1. Step 1: Write the proportion equation
   638,139.50 : 987,980 = 987,980 : x
2. Step 2: Convert to fraction form
   638,139.50/987,980 = 987,980/x
3. Step 3: Cross multiply
   638,139.50x = 987,980 × 987,980
4. Step 4: Simplify right side
   638,139.50x = 976,104,480,400
5. Step 5: Solve for x
   x = 976,104,480,400/638,139.50
6. Step 6: Final answer
   x = 1,529,609.87