Finding the Fourth Proportional to 1,017.89, 1,404.34 and 644.81

Step by Step Solution

1. Step 1: Write the proportion equation
   1,017.89 : 1,404.34 = 644.81 : x
2. Step 2: Convert to fraction form
   1,017.89/1,404.34 = 644.81/x
3. Step 3: Cross multiply
   1,017.89x = 1,404.34 × 644.81
4. Step 4: Simplify right side
   1,017.89x = 905,531.74
5. Step 5: Solve for x
   x = 905,531.74/1,017.89
6. Step 6: Final answer
   x = 889.62