Finding the Fourth Proportional to 1,385.67, 2,075.78 and 1,039.40

Step by Step Solution

1. Step 1: Write the proportion equation
   1,385.67 : 2,075.78 = 1,039.40 : x
2. Step 2: Convert to fraction form
   1,385.67/2,075.78 = 1,039.40/x
3. Step 3: Cross multiply
   1,385.67x = 2,075.78 × 1,039.40
4. Step 4: Simplify right side
   1,385.67x = 2,157,559.89
5. Step 5: Solve for x
   x = 2,157,559.89/1,385.67
6. Step 6: Final answer
   x = 1,557.05