Finding the Third Proportional to 638,139 and 987,978

Step by Step Solution

1. Step 1: Write the proportion equation
   638,139 : 987,978 = 987,978 : x
2. Step 2: Convert to fraction form
   638,139/987,978 = 987,978/x
3. Step 3: Cross multiply
   638,139x = 987,978 × 987,978
4. Step 4: Simplify right side
   638,139x = 976,100,528,484
5. Step 5: Solve for x
   x = 976,100,528,484/638,139
6. Step 6: Final answer
   x = 1,529,604.88