Finding the Fourth Proportional to 1,080.62, 1,491.27 and 638.74

Step by Step Solution

1. Step 1: Write the proportion equation
   1,080.62 : 1,491.27 = 638.74 : x
2. Step 2: Convert to fraction form
   1,080.62/1,491.27 = 638.74/x
3. Step 3: Cross multiply
   1,080.62x = 1,491.27 × 638.74
4. Step 4: Simplify right side
   1,080.62x = 952,533.80
5. Step 5: Solve for x
   x = 952,533.80/1,080.62
6. Step 6: Final answer
   x = 881.47