Finding the Fourth Proportional to 1,080.23, 1,490.67 and 638.10

Step by Step Solution

1. Step 1: Write the proportion equation
   1,080.23 : 1,490.67 = 638.10 : x
2. Step 2: Convert to fraction form
   1,080.23/1,490.67 = 638.10/x
3. Step 3: Cross multiply
   1,080.23x = 1,490.67 × 638.10
4. Step 4: Simplify right side
   1,080.23x = 951,196.53
5. Step 5: Solve for x
   x = 951,196.53/1,080.23
6. Step 6: Final answer
   x = 880.55