Finding the Third Proportional to 12,390 and 19,419

Step by Step Solution

1. Step 1: Write the proportion equation
   12,390 : 19,419 = 19,419 : x
2. Step 2: Convert to fraction form
   12,390/19,419 = 19,419/x
3. Step 3: Cross multiply
   12,390x = 19,419 × 19,419
4. Step 4: Simplify right side
   12,390x = 377,097,561
5. Step 5: Solve for x
   x = 377,097,561/12,390
6. Step 6: Final answer
   x = 30,435.64