Finding the Third Proportional to 12,960 and 20,880

Step by Step Solution

1. Step 1: Write the proportion equation
   12,960 : 20,880 = 20,880 : x
2. Step 2: Convert to fraction form
   12,960/20,880 = 20,880/x
3. Step 3: Cross multiply
   12,960x = 20,880 × 20,880
4. Step 4: Simplify right side
   12,960x = 435,974,400
5. Step 5: Solve for x
   x = 435,974,400/12,960
6. Step 6: Final answer
   x = 33,640