Finding the Fourth Proportional to 1,080.51, 1,491.03 and 638.37

Step by Step Solution

1. Step 1: Write the proportion equation
   1,080.51 : 1,491.03 = 638.37 : x
2. Step 2: Convert to fraction form
   1,080.51/1,491.03 = 638.37/x
3. Step 3: Cross multiply
   1,080.51x = 1,491.03 × 638.37
4. Step 4: Simplify right side
   1,080.51x = 951,828.82
5. Step 5: Solve for x
   x = 951,828.82/1,080.51
6. Step 6: Final answer
   x = 880.91