Finding the Third Proportional to 8,640 and 10,720

Step by Step Solution

1. Step 1: Write the proportion equation
   8,640 : 10,720 = 10,720 : x
2. Step 2: Convert to fraction form
   8,640/10,720 = 10,720/x
3. Step 3: Cross multiply
   8,640x = 10,720 × 10,720
4. Step 4: Simplify right side
   8,640x = 114,918,400
5. Step 5: Solve for x
   x = 114,918,400/8,640
6. Step 6: Final answer
   x = 13,300.74