Finding the Third Proportional to 99.59 and 218.78

Step by Step Solution

1. Step 1: Write the proportion equation
   99.59 : 218.78 = 218.78 : x
2. Step 2: Convert to fraction form
   99.59/218.78 = 218.78/x
3. Step 3: Cross multiply
   99.59x = 218.78 × 218.78
4. Step 4: Simplify right side
   99.59x = 47,865.24
5. Step 5: Solve for x
   x = 47,865.24/99.59
6. Step 6: Final answer
   x = 480.60