Finding the Third Proportional to 5,109 and 10,521

Step by Step Solution

1. Step 1: Write the proportion equation
   5,109 : 10,521 = 10,521 : x
2. Step 2: Convert to fraction form
   5,109/10,521 = 10,521/x
3. Step 3: Cross multiply
   5,109x = 10,521 × 10,521
4. Step 4: Simplify right side
   5,109x = 110,691,441
5. Step 5: Solve for x
   x = 110,691,441/5,109
6. Step 6: Final answer
   x = 21,665.97