Finding the Third Proportional to 99.50 and 217.88

Step by Step Solution

1. Step 1: Write the proportion equation
   99.50 : 217.88 = 217.88 : x
2. Step 2: Convert to fraction form
   99.50/217.88 = 217.88/x
3. Step 3: Cross multiply
   99.50x = 217.88 × 217.88
4. Step 4: Simplify right side
   99.50x = 47,469.52
5. Step 5: Solve for x
   x = 47,469.52/99.50
6. Step 6: Final answer
   x = 477.08