Finding the Third Proportional to 31,900 and 69,128

Step by Step Solution

1. Step 1: Write the proportion equation
   31,900 : 69,128 = 69,128 : x
2. Step 2: Convert to fraction form
   31,900/69,128 = 69,128/x
3. Step 3: Cross multiply
   31,900x = 69,128 × 69,128
4. Step 4: Simplify right side
   31,900x = 4,778,680,384
5. Step 5: Solve for x
   x = 4,778,680,384/31,900
6. Step 6: Final answer
   x = 149,801.89