Finding the Third Proportional to 7,920 and 12,540.38

Step by Step Solution

1. Step 1: Write the proportion equation
   7,920 : 12,540.38 = 12,540.38 : x
2. Step 2: Convert to fraction form
   7,920/12,540.38 = 12,540.38/x
3. Step 3: Cross multiply
   7,920x = 12,540.38 × 12,540.38
4. Step 4: Simplify right side
   7,920x = 157,261,005.14
5. Step 5: Solve for x
   x = 157,261,005.14/7,920
6. Step 6: Final answer
   x = 19,856.19