Finding the Third Proportional to 12,915 and 16,820

Step by Step Solution

1. Step 1: Write the proportion equation
   12,915 : 16,820 = 16,820 : x
2. Step 2: Convert to fraction form
   12,915/16,820 = 16,820/x
3. Step 3: Cross multiply
   12,915x = 16,820 × 16,820
4. Step 4: Simplify right side
   12,915x = 282,912,400
5. Step 5: Solve for x
   x = 282,912,400/12,915
6. Step 6: Final answer
   x = 21,905.72