Finding the Fourth Proportional to 1,409.92, 1,945.79 and 780.55

Step by Step Solution

1. Step 1: Write the proportion equation
   1,409.92 : 1,945.79 = 780.55 : x
2. Step 2: Convert to fraction form
   1,409.92/1,945.79 = 780.55/x
3. Step 3: Cross multiply
   1,409.92x = 1,945.79 × 780.55
4. Step 4: Simplify right side
   1,409.92x = 1,518,786.38
5. Step 5: Solve for x
   x = 1,518,786.38/1,409.92
6. Step 6: Final answer
   x = 1,077.21