Finding the Fourth Proportional to 1,443.15, 1,991.55 and 780.00

Step by Step Solution

1. Step 1: Write the proportion equation
   1,443.15 : 1,991.55 = 780.00 : x
2. Step 2: Convert to fraction form
   1,443.15/1,991.55 = 780.00/x
3. Step 3: Cross multiply
   1,443.15x = 1,991.55 × 780.00
4. Step 4: Simplify right side
   1,443.15x = 1,553,415.50
5. Step 5: Solve for x
   x = 1,553,415.50/1,443.15
6. Step 6: Final answer
   x = 1,076.40