Finding the Fourth Proportional to 1,042.59, 1,438.89 and 780.15

Step by Step Solution

1. Step 1: Write the proportion equation
   1,042.59 : 1,438.89 = 780.15 : x
2. Step 2: Convert to fraction form
   1,042.59/1,438.89 = 780.15/x
3. Step 3: Cross multiply
   1,042.59x = 1,438.89 × 780.15
4. Step 4: Simplify right side
   1,042.59x = 1,122,550.03
5. Step 5: Solve for x
   x = 1,122,550.03/1,042.59
6. Step 6: Final answer
   x = 1,076.69