Finding the Fourth Proportional to 1,139.78, 1,711.12 and 969.86

Step by Step Solution

1. Step 1: Write the proportion equation
   1,139.78 : 1,711.12 = 969.86 : x
2. Step 2: Convert to fraction form
   1,139.78/1,711.12 = 969.86/x
3. Step 3: Cross multiply
   1,139.78x = 1,711.12 × 969.86
4. Step 4: Simplify right side
   1,139.78x = 1,659,546.84
5. Step 5: Solve for x
   x = 1,659,546.84/1,139.78
6. Step 6: Final answer
   x = 1,456.02