Finding the Fourth Proportional to 1,442.89, 1,991.20 and 779.74

Step by Step Solution

1. Step 1: Write the proportion equation
   1,442.89 : 1,991.20 = 779.74 : x
2. Step 2: Convert to fraction form
   1,442.89/1,991.20 = 779.74/x
3. Step 3: Cross multiply
   1,442.89x = 1,991.20 × 779.74
4. Step 4: Simplify right side
   1,442.89x = 1,552,612.33
5. Step 5: Solve for x
   x = 1,552,612.33/1,442.89
6. Step 6: Final answer
   x = 1,076.04