Finding the Fourth Proportional to 498.94, 688.50 and 312.42

Step by Step Solution

1. Step 1: Write the proportion equation
   498.94 : 688.50 = 312.42 : x
2. Step 2: Convert to fraction form
   498.94/688.50 = 312.42/x
3. Step 3: Cross multiply
   498.94x = 688.50 × 312.42
4. Step 4: Simplify right side
   498.94x = 215,101.17
5. Step 5: Solve for x
   x = 215,101.17/498.94
6. Step 6: Final answer
   x = 431.12