Finding the Fourth Proportional to 806.39, 1,209.78 and 498.42

Step by Step Solution

1. Step 1: Write the proportion equation
   806.39 : 1,209.78 = 498.42 : x
2. Step 2: Convert to fraction form
   806.39/1,209.78 = 498.42/x
3. Step 3: Cross multiply
   806.39x = 1,209.78 × 498.42
4. Step 4: Simplify right side
   806.39x = 602,978.55
5. Step 5: Solve for x
   x = 602,978.55/806.39
6. Step 6: Final answer
   x = 747.76