Finding the Third Proportional to 389.81 and 557.72

Step by Step Solution

1. Step 1: Write the proportion equation
   389.81 : 557.72 = 557.72 : x
2. Step 2: Convert to fraction form
   389.81/557.72 = 557.72/x
3. Step 3: Cross multiply
   389.81x = 557.72 × 557.72
4. Step 4: Simplify right side
   389.81x = 311,050.20
5. Step 5: Solve for x
   x = 311,050.20/389.81
6. Step 6: Final answer
   x = 797.95