Finding the Fourth Proportional to 1,369.62, 1,890.12 and 780.18

Step by Step Solution

1. Step 1: Write the proportion equation
   1,369.62 : 1,890.12 = 780.18 : x
2. Step 2: Convert to fraction form
   1,369.62/1,890.12 = 780.18/x
3. Step 3: Cross multiply
   1,369.62x = 1,890.12 × 780.18
4. Step 4: Simplify right side
   1,369.62x = 1,474,633.82
5. Step 5: Solve for x
   x = 1,474,633.82/1,369.62
6. Step 6: Final answer
   x = 1,076.67