Finding the Fourth Proportional to 1,087.97, 1,501.55 and 639.82

Step by Step Solution

1. Step 1: Write the proportion equation
   1,087.97 : 1,501.55 = 639.82 : x
2. Step 2: Convert to fraction form
   1,087.97/1,501.55 = 639.82/x
3. Step 3: Cross multiply
   1,087.97x = 1,501.55 × 639.82
4. Step 4: Simplify right side
   1,087.97x = 960,719.57
5. Step 5: Solve for x
   x = 960,719.57/1,087.97
6. Step 6: Final answer
   x = 883.04