Finding the Fourth Proportional to 660.72, 990.72 and 336.24

Step by Step Solution

1. Step 1: Write the proportion equation
   660.72 : 990.72 = 336.24 : x
2. Step 2: Convert to fraction form
   660.72/990.72 = 336.24/x
3. Step 3: Cross multiply
   660.72x = 990.72 × 336.24
4. Step 4: Simplify right side
   660.72x = 333,119.69
5. Step 5: Solve for x
   x = 333,119.69/660.72
6. Step 6: Final answer
   x = 504.18