Finding the Fourth Proportional to 1,040.27, 1,435.39 and 642.15

Step by Step Solution

1. Step 1: Write the proportion equation
   1,040.27 : 1,435.39 = 642.15 : x
2. Step 2: Convert to fraction form
   1,040.27/1,435.39 = 642.15/x
3. Step 3: Cross multiply
   1,040.27x = 1,435.39 × 642.15
4. Step 4: Simplify right side
   1,040.27x = 921,734.08
5. Step 5: Solve for x
   x = 921,734.08/1,040.27
6. Step 6: Final answer
   x = 886.06