Finding the Third Proportional to 15,561 and 20,870

Step by Step Solution

1. Step 1: Write the proportion equation
   15,561 : 20,870 = 20,870 : x
2. Step 2: Convert to fraction form
   15,561/20,870 = 20,870/x
3. Step 3: Cross multiply
   15,561x = 20,870 × 20,870
4. Step 4: Simplify right side
   15,561x = 435,556,900
5. Step 5: Solve for x
   x = 435,556,900/15,561
6. Step 6: Final answer
   x = 27,990.29