Finding the Fourth Proportional to 1,339.78, 2,007.78 and 851.92

Step by Step Solution

1. Step 1: Write the proportion equation
   1,339.78 : 2,007.78 = 851.92 : x
2. Step 2: Convert to fraction form
   1,339.78/2,007.78 = 851.92/x
3. Step 3: Cross multiply
   1,339.78x = 2,007.78 × 851.92
4. Step 4: Simplify right side
   1,339.78x = 1,710,467.94
5. Step 5: Solve for x
   x = 1,710,467.94/1,339.78
6. Step 6: Final answer
   x = 1,276.68