Finding the Fourth Proportional to 498.79, 688.42 and 289.10

Step by Step Solution

1. Step 1: Write the proportion equation
   498.79 : 688.42 = 289.10 : x
2. Step 2: Convert to fraction form
   498.79/688.42 = 289.10/x
3. Step 3: Cross multiply
   498.79x = 688.42 × 289.10
4. Step 4: Simplify right side
   498.79x = 199,019.78
5. Step 5: Solve for x
   x = 199,019.78/498.79
6. Step 6: Final answer
   x = 399.01