Finding the Fourth Proportional to 1,311.15, 1,809.89 and 869.67

Step by Step Solution

1. Step 1: Write the proportion equation
   1,311.15 : 1,809.89 = 869.67 : x
2. Step 2: Convert to fraction form
   1,311.15/1,809.89 = 869.67/x
3. Step 3: Cross multiply
   1,311.15x = 1,809.89 × 869.67
4. Step 4: Simplify right side
   1,311.15x = 1,574,002.69
5. Step 5: Solve for x
   x = 1,574,002.69/1,311.15
6. Step 6: Final answer
   x = 1,200.47