Finding the Third Proportional to 100.31 and 217.78

Step by Step Solution

1. Step 1: Write the proportion equation
   100.31 : 217.78 = 217.78 : x
2. Step 2: Convert to fraction form
   100.31/217.78 = 217.78/x
3. Step 3: Cross multiply
   100.31x = 217.78 × 217.78
4. Step 4: Simplify right side
   100.31x = 47,428.67
5. Step 5: Solve for x
   x = 47,428.67/100.31
6. Step 6: Final answer
   x = 472.81