Finding the Fourth Proportional to 1,443.32, 1,991.78 and 780.17

Step by Step Solution

1. Step 1: Write the proportion equation
   1,443.32 : 1,991.78 = 780.17 : x
2. Step 2: Convert to fraction form
   1,443.32/1,991.78 = 780.17/x
3. Step 3: Cross multiply
   1,443.32x = 1,991.78 × 780.17
4. Step 4: Simplify right side
   1,443.32x = 1,553,916.07
5. Step 5: Solve for x
   x = 1,553,916.07/1,443.32
6. Step 6: Final answer
   x = 1,076.63