Finding the Third Proportional to 8,415 and 12,789

Step by Step Solution

1. Step 1: Write the proportion equation
   8,415 : 12,789 = 12,789 : x
2. Step 2: Convert to fraction form
   8,415/12,789 = 12,789/x
3. Step 3: Cross multiply
   8,415x = 12,789 × 12,789
4. Step 4: Simplify right side
   8,415x = 163,558,521
5. Step 5: Solve for x
   x = 163,558,521/8,415
6. Step 6: Final answer
   x = 19,436.54