Finding the Fourth Proportional to 1,311.72, 1,809.52 and 786.84

Step by Step Solution

1. Step 1: Write the proportion equation
   1,311.72 : 1,809.52 = 786.84 : x
2. Step 2: Convert to fraction form
   1,311.72/1,809.52 = 786.84/x
3. Step 3: Cross multiply
   1,311.72x = 1,809.52 × 786.84
4. Step 4: Simplify right side
   1,311.72x = 1,423,802.72
5. Step 5: Solve for x
   x = 1,423,802.72/1,311.72
6. Step 6: Final answer
   x = 1,085.45