Finding the Third Proportional to 12,912 and 19,780

Step by Step Solution

1. Step 1: Write the proportion equation
   12,912 : 19,780 = 19,780 : x
2. Step 2: Convert to fraction form
   12,912/19,780 = 19,780/x
3. Step 3: Cross multiply
   12,912x = 19,780 × 19,780
4. Step 4: Simplify right side
   12,912x = 391,248,400
5. Step 5: Solve for x
   x = 391,248,400/12,912
6. Step 6: Final answer
   x = 30,301.15