Finding the Fourth Proportional to 1,017.59, 1,404.24 and 644.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,017.59 : 1,404.24 = 644.78 : x
2. Step 2: Convert to fraction form
   1,017.59/1,404.24 = 644.78/x
3. Step 3: Cross multiply
   1,017.59x = 1,404.24 × 644.78
4. Step 4: Simplify right side
   1,017.59x = 905,418.85
5. Step 5: Solve for x
   x = 905,418.85/1,017.59
6. Step 6: Final answer
   x = 889.77