Finding the Third Proportional to 8,978 and 12,399

Step by Step Solution

1. Step 1: Write the proportion equation
   8,978 : 12,399 = 12,399 : x
2. Step 2: Convert to fraction form
   8,978/12,399 = 12,399/x
3. Step 3: Cross multiply
   8,978x = 12,399 × 12,399
4. Step 4: Simplify right side
   8,978x = 153,735,201
5. Step 5: Solve for x
   x = 153,735,201/8,978
6. Step 6: Final answer
   x = 17,123.55