Finding the Fourth Proportional to 2,385.78, 3,292.46 and 1,390.89

Step by Step Solution

1. Step 1: Write the proportion equation
   2,385.78 : 3,292.46 = 1,390.89 : x
2. Step 2: Convert to fraction form
   2,385.78/3,292.46 = 1,390.89/x
3. Step 3: Cross multiply
   2,385.78x = 3,292.46 × 1,390.89
4. Step 4: Simplify right side
   2,385.78x = 4,579,449.69
5. Step 5: Solve for x
   x = 4,579,449.69/2,385.78
6. Step 6: Final answer
   x = 1,919.48