Finding the Fourth Proportional to 1,017.71, 1,404.71 and 644.87

Step by Step Solution

1. Step 1: Write the proportion equation
   1,017.71 : 1,404.71 = 644.87 : x
2. Step 2: Convert to fraction form
   1,017.71/1,404.71 = 644.87/x
3. Step 3: Cross multiply
   1,017.71x = 1,404.71 × 644.87
4. Step 4: Simplify right side
   1,017.71x = 905,852.11
5. Step 5: Solve for x
   x = 905,852.11/1,017.71
6. Step 6: Final answer
   x = 890.09