Finding the Fourth Proportional to 1,385.78, 1,914.24 and 1,287.37

Step by Step Solution

1. Step 1: Write the proportion equation
   1,385.78 : 1,914.24 = 1,287.37 : x
2. Step 2: Convert to fraction form
   1,385.78/1,914.24 = 1,287.37/x
3. Step 3: Cross multiply
   1,385.78x = 1,914.24 × 1,287.37
4. Step 4: Simplify right side
   1,385.78x = 2,464,325.58
5. Step 5: Solve for x
   x = 2,464,325.58/1,385.78
6. Step 6: Final answer
   x = 1,778.29