Finding the Fourth Proportional to 891.69, 1,230.56 and 498.71

Step by Step Solution

1. Step 1: Write the proportion equation
   891.69 : 1,230.56 = 498.71 : x
2. Step 2: Convert to fraction form
   891.69/1,230.56 = 498.71/x
3. Step 3: Cross multiply
   891.69x = 1,230.56 × 498.71
4. Step 4: Simplify right side
   891.69x = 613,686.42
5. Step 5: Solve for x
   x = 613,686.42/891.69
6. Step 6: Final answer
   x = 688.23