Finding the Third Proportional to 31,128 and 67,215

Step by Step Solution

1. Step 1: Write the proportion equation
   31,128 : 67,215 = 67,215 : x
2. Step 2: Convert to fraction form
   31,128/67,215 = 67,215/x
3. Step 3: Cross multiply
   31,128x = 67,215 × 67,215
4. Step 4: Simplify right side
   31,128x = 4,517,856,225
5. Step 5: Solve for x
   x = 4,517,856,225/31,128
6. Step 6: Final answer
   x = 145,138.02