Finding the Third Proportional to 8,420 and 12,510

Step by Step Solution

1. Step 1: Write the proportion equation
   8,420 : 12,510 = 12,510 : x
2. Step 2: Convert to fraction form
   8,420/12,510 = 12,510/x
3. Step 3: Cross multiply
   8,420x = 12,510 × 12,510
4. Step 4: Simplify right side
   8,420x = 156,500,100
5. Step 5: Solve for x
   x = 156,500,100/8,420
6. Step 6: Final answer
   x = 18,586.71