Finding the Fourth Proportional to 2,086.74, 3,128.28 and 789.12

Step by Step Solution

1. Step 1: Write the proportion equation
   2,086.74 : 3,128.28 = 789.12 : x
2. Step 2: Convert to fraction form
   2,086.74/3,128.28 = 789.12/x
3. Step 3: Cross multiply
   2,086.74x = 3,128.28 × 789.12
4. Step 4: Simplify right side
   2,086.74x = 2,468,588.31
5. Step 5: Solve for x
   x = 2,468,588.31/2,086.74
6. Step 6: Final answer
   x = 1,182.99