Finding the Third Proportional to 287.72 and 385.69

Step by Step Solution

1. Step 1: Write the proportion equation
   287.72 : 385.69 = 385.69 : x
2. Step 2: Convert to fraction form
   287.72/385.69 = 385.69/x
3. Step 3: Cross multiply
   287.72x = 385.69 × 385.69
4. Step 4: Simplify right side
   287.72x = 148,754.85
5. Step 5: Solve for x
   x = 148,754.85/287.72
6. Step 6: Final answer
   x = 517.01