Finding the Fourth Proportional to 1,080.43, 1,490.82 and 638.30

Step by Step Solution

1. Step 1: Write the proportion equation
   1,080.43 : 1,490.82 = 638.30 : x
2. Step 2: Convert to fraction form
   1,080.43/1,490.82 = 638.30/x
3. Step 3: Cross multiply
   1,080.43x = 1,490.82 × 638.30
4. Step 4: Simplify right side
   1,080.43x = 951,590.41
5. Step 5: Solve for x
   x = 951,590.41/1,080.43
6. Step 6: Final answer
   x = 880.75