Finding the Third Proportional to 7,878 and 12,521

Step by Step Solution

1. Step 1: Write the proportion equation
   7,878 : 12,521 = 12,521 : x
2. Step 2: Convert to fraction form
   7,878/12,521 = 12,521/x
3. Step 3: Cross multiply
   7,878x = 12,521 × 12,521
4. Step 4: Simplify right side
   7,878x = 156,775,441
5. Step 5: Solve for x
   x = 156,775,441/7,878
6. Step 6: Final answer
   x = 19,900.41