Finding the Fourth Proportional to 1,017.21, 1,404.02 and 644.37

Step by Step Solution

1. Step 1: Write the proportion equation
   1,017.21 : 1,404.02 = 644.37 : x
2. Step 2: Convert to fraction form
   1,017.21/1,404.02 = 644.37/x
3. Step 3: Cross multiply
   1,017.21x = 1,404.02 × 644.37
4. Step 4: Simplify right side
   1,017.21x = 904,705.15
5. Step 5: Solve for x
   x = 904,705.15/1,017.21
6. Step 6: Final answer
   x = 889.40