Finding the Third Proportional to 31,680 and 69,648.75

Step by Step Solution

1. Step 1: Write the proportion equation
   31,680 : 69,648.75 = 69,648.75 : x
2. Step 2: Convert to fraction form
   31,680/69,648.75 = 69,648.75/x
3. Step 3: Cross multiply
   31,680x = 69,648.75 × 69,648.75
4. Step 4: Simplify right side
   31,680x = 4,850,948,376.56
5. Step 5: Solve for x
   x = 4,850,948,376.56/31,680
6. Step 6: Final answer
   x = 153,123.37