Finding the Third Proportional to 12,816 and 30,420

Step by Step Solution

1. Step 1: Write the proportion equation
   12,816 : 30,420 = 30,420 : x
2. Step 2: Convert to fraction form
   12,816/30,420 = 30,420/x
3. Step 3: Cross multiply
   12,816x = 30,420 × 30,420
4. Step 4: Simplify right side
   12,816x = 925,376,400
5. Step 5: Solve for x
   x = 925,376,400/12,816
6. Step 6: Final answer
   x = 72,204.78