Finding the Third Proportional to 12,640 and 13,720

Step by Step Solution

1. Step 1: Write the proportion equation
   12,640 : 13,720 = 13,720 : x
2. Step 2: Convert to fraction form
   12,640/13,720 = 13,720/x
3. Step 3: Cross multiply
   12,640x = 13,720 × 13,720
4. Step 4: Simplify right side
   12,640x = 188,238,400
5. Step 5: Solve for x
   x = 188,238,400/12,640
6. Step 6: Final answer
   x = 14,892.28