Finding the Fourth Proportional to 1,392.71, 1,921.37 and 861.22

Step by Step Solution

1. Step 1: Write the proportion equation
   1,392.71 : 1,921.37 = 861.22 : x
2. Step 2: Convert to fraction form
   1,392.71/1,921.37 = 861.22/x
3. Step 3: Cross multiply
   1,392.71x = 1,921.37 × 861.22
4. Step 4: Simplify right side
   1,392.71x = 1,654,719.62
5. Step 5: Solve for x
   x = 1,654,719.62/1,392.71
6. Step 6: Final answer
   x = 1,188.13