Finding the Fourth Proportional to 1,142.25, 1,577.58 and 789.15

Step by Step Solution

1. Step 1: Write the proportion equation
   1,142.25 : 1,577.58 = 789.15 : x
2. Step 2: Convert to fraction form
   1,142.25/1,577.58 = 789.15/x
3. Step 3: Cross multiply
   1,142.25x = 1,577.58 × 789.15
4. Step 4: Simplify right side
   1,142.25x = 1,244,947.26
5. Step 5: Solve for x
   x = 1,244,947.26/1,142.25
6. Step 6: Final answer
   x = 1,089.91