Finding the Third Proportional to 172.31 and 315.56

Step by Step Solution

1. Step 1: Write the proportion equation
   172.31 : 315.56 = 315.56 : x
2. Step 2: Convert to fraction form
   172.31/315.56 = 315.56/x
3. Step 3: Cross multiply
   172.31x = 315.56 × 315.56
4. Step 4: Simplify right side
   172.31x = 99,579.69
5. Step 5: Solve for x
   x = 99,579.69/172.31
6. Step 6: Final answer
   x = 577.90