Finding the Fourth Proportional to 1,311.56, 1,810.20 and 787.76

Step by Step Solution

1. Step 1: Write the proportion equation
   1,311.56 : 1,810.20 = 787.76 : x
2. Step 2: Convert to fraction form
   1,311.56/1,810.20 = 787.76/x
3. Step 3: Cross multiply
   1,311.56x = 1,810.20 × 787.76
4. Step 4: Simplify right side
   1,311.56x = 1,426,003.15
5. Step 5: Solve for x
   x = 1,426,003.15/1,311.56
6. Step 6: Final answer
   x = 1,087.26