Finding the Fourth Proportional to 1,443.21, 1,991.64 and 780.06

Step by Step Solution

1. Step 1: Write the proportion equation
   1,443.21 : 1,991.64 = 780.06 : x
2. Step 2: Convert to fraction form
   1,443.21/1,991.64 = 780.06/x
3. Step 3: Cross multiply
   1,443.21x = 1,991.64 × 780.06
4. Step 4: Simplify right side
   1,443.21x = 1,553,596.75
5. Step 5: Solve for x
   x = 1,553,596.75/1,443.21
6. Step 6: Final answer
   x = 1,076.49