Finding the Fourth Proportional to 1,391.83, 1,921.04 and 861.18

Step by Step Solution

1. Step 1: Write the proportion equation
   1,391.83 : 1,921.04 = 861.18 : x
2. Step 2: Convert to fraction form
   1,391.83/1,921.04 = 861.18/x
3. Step 3: Cross multiply
   1,391.83x = 1,921.04 × 861.18
4. Step 4: Simplify right side
   1,391.83x = 1,654,347.32
5. Step 5: Solve for x
   x = 1,654,347.32/1,391.83
6. Step 6: Final answer
   x = 1,188.62