Finding the Fourth Proportional to 1,287.45, 1,776.16 and 789.23

Step by Step Solution

1. Step 1: Write the proportion equation
   1,287.45 : 1,776.16 = 789.23 : x
2. Step 2: Convert to fraction form
   1,287.45/1,776.16 = 789.23/x
3. Step 3: Cross multiply
   1,287.45x = 1,776.16 × 789.23
4. Step 4: Simplify right side
   1,287.45x = 1,401,798.76
5. Step 5: Solve for x
   x = 1,401,798.76/1,287.45
6. Step 6: Final answer
   x = 1,088.82