Finding the Third Proportional to 12,724 and 19,890

Step by Step Solution

1. Step 1: Write the proportion equation
   12,724 : 19,890 = 19,890 : x
2. Step 2: Convert to fraction form
   12,724/19,890 = 19,890/x
3. Step 3: Cross multiply
   12,724x = 19,890 × 19,890
4. Step 4: Simplify right side
   12,724x = 395,612,100
5. Step 5: Solve for x
   x = 395,612,100/12,724
6. Step 6: Final answer
   x = 31,091.80