Finding the Fourth Proportional to 2,086.51, 3,128.72 and 787.07

Step by Step Solution

1. Step 1: Write the proportion equation
   2,086.51 : 3,128.72 = 787.07 : x
2. Step 2: Convert to fraction form
   2,086.51/3,128.72 = 787.07/x
3. Step 3: Cross multiply
   2,086.51x = 3,128.72 × 787.07
4. Step 4: Simplify right side
   2,086.51x = 2,462,502.07
5. Step 5: Solve for x
   x = 2,462,502.07/2,086.51
6. Step 6: Final answer
   x = 1,180.20