Finding the Fourth Proportional to 1,443.39, 1,991.88 and 780.24

Step by Step Solution

1. Step 1: Write the proportion equation
   1,443.39 : 1,991.88 = 780.24 : x
2. Step 2: Convert to fraction form
   1,443.39/1,991.88 = 780.24/x
3. Step 3: Cross multiply
   1,443.39x = 1,991.88 × 780.24
4. Step 4: Simplify right side
   1,443.39x = 1,554,140.55
5. Step 5: Solve for x
   x = 1,554,140.55/1,443.39
6. Step 6: Final answer
   x = 1,076.73