Finding the Third Proportional to 8,720 and 13,200

Step by Step Solution

1. Step 1: Write the proportion equation
   8,720 : 13,200 = 13,200 : x
2. Step 2: Convert to fraction form
   8,720/13,200 = 13,200/x
3. Step 3: Cross multiply
   8,720x = 13,200 × 13,200
4. Step 4: Simplify right side
   8,720x = 174,240,000
5. Step 5: Solve for x
   x = 174,240,000/8,720
6. Step 6: Final answer
   x = 19,981.65