Finding the Fourth Proportional to 1,311.57, 1,810.53 and 787.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,311.57 : 1,810.53 = 787.50 : x
2. Step 2: Convert to fraction form
   1,311.57/1,810.53 = 787.50/x
3. Step 3: Cross multiply
   1,311.57x = 1,810.53 × 787.50
4. Step 4: Simplify right side
   1,311.57x = 1,425,792.38
5. Step 5: Solve for x
   x = 1,425,792.38/1,311.57
6. Step 6: Final answer
   x = 1,087.09