Finding the Fourth Proportional to 1,046.70, 1,443.78 and 642.75

Step by Step Solution

1. Step 1: Write the proportion equation
   1,046.70 : 1,443.78 = 642.75 : x
2. Step 2: Convert to fraction form
   1,046.70/1,443.78 = 642.75/x
3. Step 3: Cross multiply
   1,046.70x = 1,443.78 × 642.75
4. Step 4: Simplify right side
   1,046.70x = 927,989.60
5. Step 5: Solve for x
   x = 927,989.60/1,046.70
6. Step 6: Final answer
   x = 886.59