Finding the Fourth Proportional to 2,086.40, 3,128.76 and 787.16

Step by Step Solution

1. Step 1: Write the proportion equation
   2,086.40 : 3,128.76 = 787.16 : x
2. Step 2: Convert to fraction form
   2,086.40/3,128.76 = 787.16/x
3. Step 3: Cross multiply
   2,086.40x = 3,128.76 × 787.16
4. Step 4: Simplify right side
   2,086.40x = 2,462,834.72
5. Step 5: Solve for x
   x = 2,462,834.72/2,086.40
6. Step 6: Final answer
   x = 1,180.42