Finding the Third Proportional to 12,740 and 19,678

Step by Step Solution

1. Step 1: Write the proportion equation
   12,740 : 19,678 = 19,678 : x
2. Step 2: Convert to fraction form
   12,740/19,678 = 19,678/x
3. Step 3: Cross multiply
   12,740x = 19,678 × 19,678
4. Step 4: Simplify right side
   12,740x = 387,223,684
5. Step 5: Solve for x
   x = 387,223,684/12,740
6. Step 6: Final answer
   x = 30,394.32