Finding the Fourth Proportional to 498.78, 688.29 and 274.71

Step by Step Solution

1. Step 1: Write the proportion equation
   498.78 : 688.29 = 274.71 : x
2. Step 2: Convert to fraction form
   498.78/688.29 = 274.71/x
3. Step 3: Cross multiply
   498.78x = 688.29 × 274.71
4. Step 4: Simplify right side
   498.78x = 189,080.15
5. Step 5: Solve for x
   x = 189,080.15/498.78
6. Step 6: Final answer
   x = 379.09