Finding the Third Proportional to 115.31 and 216.56

Step by Step Solution

1. Step 1: Write the proportion equation
   115.31 : 216.56 = 216.56 : x
2. Step 2: Convert to fraction form
   115.31/216.56 = 216.56/x
3. Step 3: Cross multiply
   115.31x = 216.56 × 216.56
4. Step 4: Simplify right side
   115.31x = 46,899.32
5. Step 5: Solve for x
   x = 46,899.32/115.31
6. Step 6: Final answer
   x = 406.71