Finding the Fourth Proportional to 891.60, 1,230.42 and 498.61

Step by Step Solution

1. Step 1: Write the proportion equation
   891.60 : 1,230.42 = 498.61 : x
2. Step 2: Convert to fraction form
   891.60/1,230.42 = 498.61/x
3. Step 3: Cross multiply
   891.60x = 1,230.42 × 498.61
4. Step 4: Simplify right side
   891.60x = 613,499.72
5. Step 5: Solve for x
   x = 613,499.72/891.60
6. Step 6: Final answer
   x = 688.09