Finding the Fourth Proportional to 1,369.58, 1,889.91 and 780.12

Step by Step Solution

1. Step 1: Write the proportion equation
   1,369.58 : 1,889.91 = 780.12 : x
2. Step 2: Convert to fraction form
   1,369.58/1,889.91 = 780.12/x
3. Step 3: Cross multiply
   1,369.58x = 1,889.91 × 780.12
4. Step 4: Simplify right side
   1,369.58x = 1,474,356.59
5. Step 5: Solve for x
   x = 1,474,356.59/1,369.58
6. Step 6: Final answer
   x = 1,076.51