Finding the Fourth Proportional to 1,312.72, 1,810.90 and 787.84

Step by Step Solution

1. Step 1: Write the proportion equation
   1,312.72 : 1,810.90 = 787.84 : x
2. Step 2: Convert to fraction form
   1,312.72/1,810.90 = 787.84/x
3. Step 3: Cross multiply
   1,312.72x = 1,810.90 × 787.84
4. Step 4: Simplify right side
   1,312.72x = 1,426,699.46
5. Step 5: Solve for x
   x = 1,426,699.46/1,312.72
6. Step 6: Final answer
   x = 1,086.83