Finding the Fourth Proportional to 1,080.77, 1,491.57 and 638.82

Step by Step Solution

1. Step 1: Write the proportion equation
   1,080.77 : 1,491.57 = 638.82 : x
2. Step 2: Convert to fraction form
   1,080.77/1,491.57 = 638.82/x
3. Step 3: Cross multiply
   1,080.77x = 1,491.57 × 638.82
4. Step 4: Simplify right side
   1,080.77x = 952,844.75
5. Step 5: Solve for x
   x = 952,844.75/1,080.77
6. Step 6: Final answer
   x = 881.64