Finding the Fourth Proportional to 1,327.78, 1,992.73 and 780.42

Step by Step Solution

1. Step 1: Write the proportion equation
   1,327.78 : 1,992.73 = 780.42 : x
2. Step 2: Convert to fraction form
   1,327.78/1,992.73 = 780.42/x
3. Step 3: Cross multiply
   1,327.78x = 1,992.73 × 780.42
4. Step 4: Simplify right side
   1,327.78x = 1,555,152.48
5. Step 5: Solve for x
   x = 1,555,152.48/1,327.78
6. Step 6: Final answer
   x = 1,171.25