Finding the Third Proportional to 172.31 and 399.56

Step by Step Solution

1. Step 1: Write the proportion equation
   172.31 : 399.56 = 399.56 : x
2. Step 2: Convert to fraction form
   172.31/399.56 = 399.56/x
3. Step 3: Cross multiply
   172.31x = 399.56 × 399.56
4. Step 4: Simplify right side
   172.31x = 159,650.19
5. Step 5: Solve for x
   x = 159,650.19/172.31
6. Step 6: Final answer
   x = 926.52