Finding the Third Proportional to 5,400 and 10,800

Step by Step Solution

1. Step 1: Write the proportion equation
   5,400 : 10,800 = 10,800 : x
2. Step 2: Convert to fraction form
   5,400/10,800 = 10,800/x
3. Step 3: Cross multiply
   5,400x = 10,800 × 10,800
4. Step 4: Simplify right side
   5,400x = 116,640,000
5. Step 5: Solve for x
   x = 116,640,000/5,400
6. Step 6: Final answer
   x = 21,600