Finding the Fourth Proportional to 1,017.30, 1,404.07 and 644.71

Step by Step Solution

1. Step 1: Write the proportion equation
   1,017.30 : 1,404.07 = 644.71 : x
2. Step 2: Convert to fraction form
   1,017.30/1,404.07 = 644.71/x
3. Step 3: Cross multiply
   1,017.30x = 1,404.07 × 644.71
4. Step 4: Simplify right side
   1,017.30x = 905,214.12
5. Step 5: Solve for x
   x = 905,214.12/1,017.30
6. Step 6: Final answer
   x = 889.82