Finding the Fourth Proportional to 1,139.89, 1,571.52 and 890.23

Step by Step Solution

1. Step 1: Write the proportion equation
   1,139.89 : 1,571.52 = 890.23 : x
2. Step 2: Convert to fraction form
   1,139.89/1,571.52 = 890.23/x
3. Step 3: Cross multiply
   1,139.89x = 1,571.52 × 890.23
4. Step 4: Simplify right side
   1,139.89x = 1,399,014.25
5. Step 5: Solve for x
   x = 1,399,014.25/1,139.89
6. Step 6: Final answer
   x = 1,227.32