Finding the Third Proportional to 6,390 and 13,890

Step by Step Solution

1. Step 1: Write the proportion equation
   6,390 : 13,890 = 13,890 : x
2. Step 2: Convert to fraction form
   6,390/13,890 = 13,890/x
3. Step 3: Cross multiply
   6,390x = 13,890 × 13,890
4. Step 4: Simplify right side
   6,390x = 192,932,100
5. Step 5: Solve for x
   x = 192,932,100/6,390
6. Step 6: Final answer
   x = 30,192.82