Finding the Fourth Proportional to 498.72, 688.27 and 288.96

Step by Step Solution

1. Step 1: Write the proportion equation
   498.72 : 688.27 = 288.96 : x
2. Step 2: Convert to fraction form
   498.72/688.27 = 288.96/x
3. Step 3: Cross multiply
   498.72x = 688.27 × 288.96
4. Step 4: Simplify right side
   498.72x = 198,882.50
5. Step 5: Solve for x
   x = 198,882.50/498.72
6. Step 6: Final answer
   x = 398.79