Finding the Fourth Proportional to 1,369.91, 1,890.50 and 780.59

Step by Step Solution

1. Step 1: Write the proportion equation
   1,369.91 : 1,890.50 = 780.59 : x
2. Step 2: Convert to fraction form
   1,369.91/1,890.50 = 780.59/x
3. Step 3: Cross multiply
   1,369.91x = 1,890.50 × 780.59
4. Step 4: Simplify right side
   1,369.91x = 1,475,692.04
5. Step 5: Solve for x
   x = 1,475,692.04/1,369.91
6. Step 6: Final answer
   x = 1,077.22