Finding the Third Proportional to 8,640 and 13,780

Step by Step Solution

1. Step 1: Write the proportion equation
   8,640 : 13,780 = 13,780 : x
2. Step 2: Convert to fraction form
   8,640/13,780 = 13,780/x
3. Step 3: Cross multiply
   8,640x = 13,780 × 13,780
4. Step 4: Simplify right side
   8,640x = 189,888,400
5. Step 5: Solve for x
   x = 189,888,400/8,640
6. Step 6: Final answer
   x = 21,977.82