Finding the Fourth Proportional to 1,080.53, 1,491.05 and 638.34

Step by Step Solution

1. Step 1: Write the proportion equation
   1,080.53 : 1,491.05 = 638.34 : x
2. Step 2: Convert to fraction form
   1,080.53/1,491.05 = 638.34/x
3. Step 3: Cross multiply
   1,080.53x = 1,491.05 × 638.34
4. Step 4: Simplify right side
   1,080.53x = 951,796.86
5. Step 5: Solve for x
   x = 951,796.86/1,080.53
6. Step 6: Final answer
   x = 880.86