Finding the Fourth Proportional to 1,369.80, 1,890.24 and 780.38

Step by Step Solution

1. Step 1: Write the proportion equation
   1,369.80 : 1,890.24 = 780.38 : x
2. Step 2: Convert to fraction form
   1,369.80/1,890.24 = 780.38/x
3. Step 3: Cross multiply
   1,369.80x = 1,890.24 × 780.38
4. Step 4: Simplify right side
   1,369.80x = 1,475,105.49
5. Step 5: Solve for x
   x = 1,475,105.49/1,369.80
6. Step 6: Final answer
   x = 1,076.88