Finding the Fourth Proportional to 1,289.55, 1,779.83 and 765.87

Step by Step Solution

1. Step 1: Write the proportion equation
   1,289.55 : 1,779.83 = 765.87 : x
2. Step 2: Convert to fraction form
   1,289.55/1,779.83 = 765.87/x
3. Step 3: Cross multiply
   1,289.55x = 1,779.83 × 765.87
4. Step 4: Simplify right side
   1,289.55x = 1,363,114.57
5. Step 5: Solve for x
   x = 1,363,114.57/1,289.55
6. Step 6: Final answer
   x = 1,057.05