Finding the Third Proportional to 12,780 and 19,740

Step by Step Solution

1. Step 1: Write the proportion equation
   12,780 : 19,740 = 19,740 : x
2. Step 2: Convert to fraction form
   12,780/19,740 = 19,740/x
3. Step 3: Cross multiply
   12,780x = 19,740 × 19,740
4. Step 4: Simplify right side
   12,780x = 389,667,600
5. Step 5: Solve for x
   x = 389,667,600/12,780
6. Step 6: Final answer
   x = 30,490.42