Finding the Third Proportional to 99.31 and 217.85

Step by Step Solution

1. Step 1: Write the proportion equation
   99.31 : 217.85 = 217.85 : x
2. Step 2: Convert to fraction form
   99.31/217.85 = 217.85/x
3. Step 3: Cross multiply
   99.31x = 217.85 × 217.85
4. Step 4: Simplify right side
   99.31x = 47,456.75
5. Step 5: Solve for x
   x = 47,456.75/99.31
6. Step 6: Final answer
   x = 477.86