Finding the Fourth Proportional to 1,080.95, 1,490.81 and 638.42

Step by Step Solution

1. Step 1: Write the proportion equation
   1,080.95 : 1,490.81 = 638.42 : x
2. Step 2: Convert to fraction form
   1,080.95/1,490.81 = 638.42/x
3. Step 3: Cross multiply
   1,080.95x = 1,490.81 × 638.42
4. Step 4: Simplify right side
   1,080.95x = 951,752.27
5. Step 5: Solve for x
   x = 951,752.27/1,080.95
6. Step 6: Final answer
   x = 880.48