Finding the Third Proportional to 354.28 and 542.72

Step by Step Solution

1. Step 1: Write the proportion equation
   354.28 : 542.72 = 542.72 : x
2. Step 2: Convert to fraction form
   354.28/542.72 = 542.72/x
3. Step 3: Cross multiply
   354.28x = 542.72 × 542.72
4. Step 4: Simplify right side
   354.28x = 294,543.64
5. Step 5: Solve for x
   x = 294,543.64/354.28
6. Step 6: Final answer
   x = 831.38