Finding the Fourth Proportional to 1,789.78, 2,470.83 and 1,390.55

Step by Step Solution

1. Step 1: Write the proportion equation
   1,789.78 : 2,470.83 = 1,390.55 : x
2. Step 2: Convert to fraction form
   1,789.78/2,470.83 = 1,390.55/x
3. Step 3: Cross multiply
   1,789.78x = 2,470.83 × 1,390.55
4. Step 4: Simplify right side
   1,789.78x = 3,435,812.66
5. Step 5: Solve for x
   x = 3,435,812.66/1,789.78
6. Step 6: Final answer
   x = 1,919.68