Finding the Fourth Proportional to 1,390.83, 1,920.78 and 1,203.42

Step by Step Solution

1. Step 1: Write the proportion equation
   1,390.83 : 1,920.78 = 1,203.42 : x
2. Step 2: Convert to fraction form
   1,390.83/1,920.78 = 1,203.42/x
3. Step 3: Cross multiply
   1,390.83x = 1,920.78 × 1,203.42
4. Step 4: Simplify right side
   1,390.83x = 2,311,505.07
5. Step 5: Solve for x
   x = 2,311,505.07/1,390.83
6. Step 6: Final answer
   x = 1,661.96