Finding the Fourth Proportional to 1,123.31, 1,550.31 and 644.95

Step by Step Solution

1. Step 1: Write the proportion equation
   1,123.31 : 1,550.31 = 644.95 : x
2. Step 2: Convert to fraction form
   1,123.31/1,550.31 = 644.95/x
3. Step 3: Cross multiply
   1,123.31x = 1,550.31 × 644.95
4. Step 4: Simplify right side
   1,123.31x = 999,877.40
5. Step 5: Solve for x
   x = 999,877.40/1,123.31
6. Step 6: Final answer
   x = 890.12