Finding the Fourth Proportional to 1,017.57, 1,403.49 and 644.61

Step by Step Solution

1. Step 1: Write the proportion equation
   1,017.57 : 1,403.49 = 644.61 : x
2. Step 2: Convert to fraction form
   1,017.57/1,403.49 = 644.61/x
3. Step 3: Cross multiply
   1,017.57x = 1,403.49 × 644.61
4. Step 4: Simplify right side
   1,017.57x = 904,703.69
5. Step 5: Solve for x
   x = 904,703.69/1,017.57
6. Step 6: Final answer
   x = 889.08