Finding the Fourth Proportional to 2,072.78, 3,107.54 and 840.50

Step by Step Solution

1. Step 1: Write the proportion equation
   2,072.78 : 3,107.54 = 840.50 : x
2. Step 2: Convert to fraction form
   2,072.78/3,107.54 = 840.50/x
3. Step 3: Cross multiply
   2,072.78x = 3,107.54 × 840.50
4. Step 4: Simplify right side
   2,072.78x = 2,611,887.37
5. Step 5: Solve for x
   x = 2,611,887.37/2,072.78
6. Step 6: Final answer
   x = 1,260.09