Finding the Third Proportional to 12,890 and 17,139

Step by Step Solution

1. Step 1: Write the proportion equation
   12,890 : 17,139 = 17,139 : x
2. Step 2: Convert to fraction form
   12,890/17,139 = 17,139/x
3. Step 3: Cross multiply
   12,890x = 17,139 × 17,139
4. Step 4: Simplify right side
   12,890x = 293,745,321
5. Step 5: Solve for x
   x = 293,745,321/12,890
6. Step 6: Final answer
   x = 22,788.62