Finding the Fourth Proportional to 1,439.43, 2,155.60 and 917.89

Step by Step Solution

1. Step 1: Write the proportion equation
   1,439.43 : 2,155.60 = 917.89 : x
2. Step 2: Convert to fraction form
   1,439.43/2,155.60 = 917.89/x
3. Step 3: Cross multiply
   1,439.43x = 2,155.60 × 917.89
4. Step 4: Simplify right side
   1,439.43x = 1,978,594.28
5. Step 5: Solve for x
   x = 1,978,594.28/1,439.43
6. Step 6: Final answer
   x = 1,374.57